physician who introduced smallpox inoculation into the American colonies. Inoculation consisted of collecting a small quantity of pustular material from a smallpox victim and introducing it into the arm of one who had not had the disease. The result was usually a mild case that conferred lifelong protection.

During the Boston smallpox epidemic of 1721, Boylston was urged to begin inoculations of the virus by the minister Cotton Mather (Mather, Cotton), who had heard reports from Europe of their use in Turkey. Boylston responded enthusiastically, beginning with his own family and eventually inoculating about 250 people. The practice was so bitterly opposed by other physicians, the clergy, and much of the populace that Boylston's life was threatened and he was forced to perform his work in great secrecy.

Of those inoculated by Boylston, only six died of smallpox—a much lower mortality rate than expected during an epidemic. Boylston traveled to London in 1724 and was elected to the Royal Society in 1726. His account of the Boston epidemic is a model of clarity.