Healthcare in London, which consumes about a fifth of the NHS budget in England, is in many respects distinct from that in the rest of the United Kingdom, or England.

The earliest state hospitals in the UK were set up in London under the management of the Metropolitan Asylums Board which was established by the Metropolitan Poor Act 1867 (30 & 31 Vict. c. 6). They supplemented the pattern of voluntary hospitals which had developed in the case of St Bartholomew's Hospital since 1123. Florence Nightingale campaigned to establish accommodation in infirmaries for the sick separate from that provided by workhouses. She had formulated her schemes for immediate application to London because it was obvious that sweeping reforms could not be absorbed at once throughout the country. In 1860, she proved successful in her campaign and founded, in London, the world's first secular nursing school connected to a fully serving hospital and medical school (St. Thomas' Hospital).

Sanatorium benefit was a particular feature of the National Insurance Act 1911. The Metropolitan Asylums Board had established some 8,500 isolation beds and it was agreed that these beds could be used to meet the obligations of the London County Council. The Board was eventually dissolved in March 1930 as a result of the Local Government Act 1929 and its 24,000 beds transferred to the Council. The Local Government Act permitted, but did not compel, local authorities to take over Poor Law institutions, and to bring some measure of order into an expanded municipal hospital system. This opportunity was exploited by the LCC, which by 1936 had become a stronghold for members of the Socialist Medical Association. Somerville Hastings, President of the SMA, was chairman of the LCC's hospital committee. "The LCC constituted a crucible for experiment, a state within the medical state" which informed the Ministry of Health during the evolution of its thinking on a comprehensive health service. The expansion of health services by the LCC resulted in the maternal death rate per thousand births falling dramatically, from 7.2 in 1932 to 2.49 in 1937 and London under Labour going from well above to below the national average.

Attempts to map deprivation in the city date back at least to London Labour and the London Poor in the 1840s, if not to Defoe's A Journal of the Plague Year of 1722. More recently there has been some powerful use of the London Underground as a method of illustration. Life expectancy famously varies, often by several years, between one tube station and the next.

London has the highest rates of childhood obesity of any comparable global city. Healthy eating messages in schools are overwhelmed by the temptations of more than 8,000 fast food outlets – with around 800 more opening every year.

London illustrated the difficulties which would flow from the market model. The 1990 NHS reforms precipitated a crisis in London which necessitated emergency action in the form of the Tomlinson review of London health services. There were severe restrictions on competition. Purchasers were instructed to maintain a "steady state" and the terminology was altered to play down market connotations.

In 1993 the Tomlinson review of London hospitals was published and concluded that there were too many hospitals in central London. It recommended that services should be delivered closer to where people lived and that funds should be made available to raise the standard of GP premises in inner London. Several hospitals were threatened with closure. Although Tomlinson claimed that he had "found an acceptance of the need for change" in fact the proposals were largely rejected.

Frank Dobson commissioned Sir Leslie Turnberg and a panel to undertake a strategic review of health services in the capital in 1997. The report particularly stressed the degree to which primary care in the capital was lagging behind the rest of the country, but the focus of the government continued to be on hospitals.