Raw milk or unpasteurized milk is milk that has not undergone pasteurization, a process of heating liquid foods to kill pathogens for safe consumption and extension of shelf life.

Proponents of raw milk have alleged numerous purported benefits to consumption, including better flavor, better nutrition, contributions to the building of a healthy immune system and protection from allergies. However, no clear benefit to consumption has been found. In contrast, broad consensus in the medical community warns that there is an increased risk of contracting dangerous milk borne diseases from these products. Substantial evidence of this increased risk, combined with a lack of any clear benefit, has led countries around the world to either prohibit the sale of raw milk or require warning labels on packaging when sold.

In countries where it is available for sale, its availability and regulations around its sale vary. In the European Union, individual member states can prohibit or restrict the sale of raw milk, but it is not banned outright; in some member states, the sale of raw milk through vending machines is permitted, though the packaging will typically instruct consumers to boil before consumption.

Humans first learned to regularly consume the milk of other mammals following the domestication of animals during the Neolithic Revolution or the development of agriculture. This development occurred independently in several places around the world from as early as 9000–7000 BC in Mesopotamia to 3500–3000 BC in the Americas. The most important dairy animals—cattle, sheep and goats—were first domesticated in Mesopotamia, although domestic cattle had been independently derived from wild aurochs populations several times since. From there, dairy animals spread to Europe (beginning around 7000 BC but not reaching Britain and Scandinavia until after 4000 BC), and South Asia (7000–5500 BC).

Pasteurization is widely used to prevent infected milk from entering the food supply. The pasteurization process was developed in 1864 by French scientist Louis Pasteur, who discovered that heating beer and wine was enough to kill most of the bacteria that caused spoilage, preventing these beverages from turning sour. The process achieves this by eliminating pathogenic microbes and lowering microbial numbers to prolong the quality of the beverage.

After sufficient scientific study led to the development of germ theory, pasteurization was introduced in the United States in the 1890s. This move successfully controlled the spread of highly contagious bacterial diseases, including E. coli, bovine tuberculosis, and brucellosis (all thought to be easily transmitted to humans through the drinking of raw milk). In the early days after the scientific discovery of bacteria, there was no product testing to determine whether a farmer's milk was safe or infected, so all milk was treated as potentially contagious. After the first tests were developed, some farmers took steps to prevent their infected animals from being killed and removed from food production, sometimes even falsifying test results to make their animals appear free of infection. Recent advances in the analysis of milk-borne diseases have enabled scientists to track the DNA of the infectious bacteria to the cows on the farms that supplied the raw milk.

The recognition of many potentially deadly pathogens, such as E. coli 0157 H7, Campylobacter, Listeria, and Salmonella, and their possible presence in poorly produced milk products has led to the continuation of pasteurization. The U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, and other health agencies of the United States strongly recommend that the public not consume raw milk or raw milk products. Young children, the elderly, people with weakened immune systems, and pregnant women are more susceptible to infections originating in raw milk.

Some cheeses are produced with raw milk, although local statutes vary regarding what health precautions must be followed, such as aging cheese for a certain amount of time.