One daughter, Agnes was married to James Mylne, professor of moral philosophy at Glasgow, and another, Margaret, to Dr. John Thomson, by whom she was mother of Allan Thomson, professor of surgery at Edinburgh. He left his manuscripts to his eldest son, to Professor Mylne, and to John Craig, his nephew, by whom some were published in 1803. In 1985 the John Millar Chair of Law at the University of Glasgow was established in his memory.