Dahl was married to Patricia Neal from 1953 until they divorced in 1983. They had four daughters (one of whom died before them) and a son. Dahl was married to Felicity Crosland from 1983 until his death. He lived in Great Missenden, Buckinghamshire. He died on 23 November 1990 in Oxford, from myelodysplastic syndrome, aged 74.