The Highland Potato Famine (Scottish Gaelic: Gaiseadh a' bhuntàta) was a period of 19th-century Scottish Highland history (1846 to roughly 1856) over which the agricultural communities of the Hebrides and the western Scottish Highlands (Gàidhealtachd) saw their potato crop (upon which they had become over-reliant) repeatedly devastated by potato blight. It was part of the wider food crisis facing Northern Europe caused by potato blight during the mid-1840s, whose most famous manifestation is the Great Irish Famine, but compared with its Irish counterpart, it was much less extensive (the population seriously at risk was never more than 200,000 – and often much less) and took many fewer lives as prompt and major charitable efforts by the rest of the United Kingdom ensured relatively little starvation.

The terms on which charitable relief was given, however, led to destitution and malnutrition amongst its recipients. A government enquiry could suggest no short-term solution other than reduction of the population of the area at risk by emigration to Canada or Australia. Highland landlords organised and paid for the emigration of more than 16,000 of their tenants and a significant but unknown number paid for their own passage. Evidence suggests that the majority of Highlanders who permanently left the famine-struck regions emigrated, rather than moving to other parts of Scotland. It is estimated that about a third of the population of the western Scottish Highlands emigrated between 1841 and 1861.

Over the late 18th and early 19th century, Highland society had changed greatly. On the eastern fringes of the Highlands, most arable land was divided into family farms with 20 to 50 acres (8.1 to 20.2 hectares) employing crofters (with some land held in their own right, insufficient on its own to give them an adequate living) and cottars (farm workers with no land of their own, sometimes sub-let a small patch of land by their employer or a crofter). The economy had become assimilated to that of the Lowlands, whose proximity allowed and encouraged a diverse agriculture. Proximity to the Lowlands had also led to a steady drain of population from these areas. In the Western Isles and the adjacent mainland developments had been very different. Chieftains who had become improving landlords had found livestock-grazing (generally sheep, sometimes cattle) the most remunerative form of agriculture; to accommodate this they had moved their tenants to coastal townships where they hoped valuable industries could be developed and established an extensive crofting system (see Highland Clearances). Croft sizes were set low to encourage the tenantry to participate in the industry (e.g. fishing, kelp) the landlord wished to develop.

A contemporary writer thought that a crofter would have to do work away from his holding for 200 days a year if his family were to avoid destitution. The various industries the crofting townships were supposed to support mostly prospered in the first quarter of the 19th century (drawing workers over and above the originally intended population of townships) but declined or collapsed over its second quarter. The crofting areas were correspondingly impoverished, but able to sustain themselves by a much greater reliance on potatoes (it was reckoned that one acre growing potatoes could support as many people as four acres growing oats). Between 1801 and 1841 the population in the crofting area increased by over half, whereas in the eastern and southern Highlands the increase in the same period was under 10 percent. Consequently, immediately pre-blight, whilst mainland Argyll had over 2 acres (0.8 hectares) of arable land per inhabitant, there was only 1⁄2 acre (0.2 hectares) of arable land per head in Skye and Wester Ross: in the crofting area, as in Ireland, the population had grown to levels which only a successful potato harvest could support.

In the Scottish Highlands, in 1846, there was widespread failure of potato crops as a result of potato blight. Crops failed in about three-quarters of the crofting region, putting a population of about 200,000 at risk; the following winter was especially cold and snowy and the death rate rose significantly. The Free Church of Scotland, strong in the affected areas, was prompt in raising the alarm and in organising relief, being the only body actively doing so in late 1846 and early 1847; relief was given regardless of denomination. Additionally, the Free Church organised transport for over 3,000 men from the famine-struck regions to work on the Lowland railways. This both removed people who needed to be fed from the area and provided money for their families to buy food.

The British government took early notice of the crop failure. They were approached for assistance by landowners at the end of the summer of 1846, but any direct subsidies to the landlords were ruled out, as this would have relieved them of their responsibilities to their tenants. Sir Charles Trevelyan, the Assistant Secretary to the Treasury (effectively the senior civil servant at this department) provided the lead. The government was restricted by the common attitudes of the middle of the 19th century: minimal intervention, and there was deep concern to avoid upsetting the free play of normal market forces. Despite the constraints of these ruling economic theories, Trevelyan made completely clear that "the people cannot, under any circumstances, be allowed to starve" in a letter of September 1846.

The government's first action was to ensure that Highland landlord met their responsibilities to provide famine relief to their tenants. Landlord response varied. Some had both the resources and the willingness to do this. Others, typically among the remaining hereditary landowners, were in perilous financial conditions and struggled to meet expectations, some of them being in denial about their lack of ability to do so. The last class, those who had the means to fund relief for their tenants, but chose not to, were put under substantial pressure by the government. Senior relief officers made personal inspections of their properties (the Royal Navy had a steamer to provide transport for this). Formal exhortations were made over the winter of 1846 to those who still did not comply. Threats were added that the government would recover the costs of relief they had provided, even by selling part of the problem estates. By mid-1847, even the notorious Colonel John Gordon of Cluny was acknowledged by the senior relief officer, Sir Edward Pine Coffin, as having improved beyond the worst class of landlord.

The government stationed two meal depots at Portree and Tobermory in the winter of 1846-7 and based a team of relief officers in the affected areas. The depots sold meal only at market prices - any hint of a subsidy went against free market principles. However, the purpose in establishing the depots was to prevent spiralling prices due to local shortages - thereby demonstrating the dilemma in choosing practical, necessary measures that fitted with the contemporary views on political economy. Existing legislation was examined for ways of providing help. Innovative measures were shunned for fear of expanding the role of government. Discretion was allowed to Inspectors of the Poor in providing meal to recipients of casual relief for destitute families. A much larger use of current law was the active encouragement of landowners to apply for loans under the Drainage and Public Works Act. After streamlining of the cumbersome application process, this channelled money to landlords that allowed them to employ their tenantry to improve the land that they rented.