Zabdiel Boylston (1679-1766) was the first American physician to use inoculation against smallpox in 1721 during a Boston epidemic.

Zabdiel Boylston was born March 9, 1679, near the present city of Brookline, Mass., and studied medicine with his father, Dr. Thomas Boylston, and a Dr. Cutter of Boston. He married Jerusha Minot in January 1705; they had eight children. Little is known of his career until June 1721. On April 15 of that year a smallpox epidemic had broken out in Boston. Cotton Mather had a slave named Onesimus, who had informed him that inoculation with the disease was commonly used in Africa to prevent a later, severe case. Mather circulated this information to the Boston medical community by pamphlet and on June 24 wrote Boylston, urging him to begin inoculation. On June 26 Boylston inoculated his son and two servants, and for several months he inoculated others.

Opposition against Boylston and Mather soon led to damage to their houses and an extensive pamphlet war. Though Boylston was called before the selectmen three times to explain his actions, the pamphlets, some jointly written, but mostly by Mather, began to convince many people of the value of inoculation. By February, 241 persons had been inoculated by Boylston; only six died of smallpox, four of whom had contracted the disease before inoculation.

His activities attracted the attention of Sir Hans Sloan in London, where similar experiments were taking place. Sloan invited Boylston to spend the years 1724-1726 in London, lecturing to the Royal College of physicians and working on his book, An Historical Account of the Small-pox Inoculated in New England, published in 1726. He also addressed the Royal Society, of which he was made a member in 1726. His account, republished in Boston in 1730, was very carefully documented, the first systematic clinical presentation by an American physician.

On his return to Boston in 1726, Boylston did little more of note. He corresponded with his European friends, inoculated occasionally when epidemics broke out, and retired in the 1740s. He spent his last years raising horses. He died March 1, 1766, after several years of pulmonary illness.