Only 5 US Presidents were ever childless, and that only in the sense of biological children:1. George Washington, notably, had no biological children, all of his heirs being from Martha's first marriage to Daniel Parke Custis (1711-1757).4. James Madison had no biological children. His adopted son John (Payne) Todd was his wife Dolley's son. Her husband John Todd Jr. and infant son William had died in an epidemic in 1793.7. Andrew Jackson and his wife had no children of their own, but cared for children of relatives including Jackson's nephew.11. James Polk and Sarah Polk never had children. (They did have a legal ward, who was the president's nephew.)15. James Buchanan never married or had children. He did adopt two of his nieces however.NOTE - two more Presidents were childless in office, one had a child out of wedlock14. Franklin Pierce had three sons but all died as children, the oldest at age 11 just after his election.25. William McKinley had two daughters but both died before he was President (one in infancy, one at age three).29. Warren G. Harding apparently had a daughter, Elizabeth, by his mistress Nan Britton. His stepson was Marshall DeWolfe, from his wife's first marriage.