The men's marathon at the 1988 Summer Olympics in Seoul, South Korea was held on Sunday October 2, 1988.

Kenya (Douglas Wakiihuri's silver) and Djibouti (Hussein Ahmed Salah's bronze) each won their first Olympic men's marathon medal.

Returning runners from the 1984 marathon included silver medalist John Treacy of Ireland, bronze medalist Charlie Spedding of Great Britain, fifth-place finisher Robert de Castella of Australia, and sixth-place finisher Juma Ikangaa of Tanzania.

The favorites included de Castella, Gelindo Bordin of Italy, and rising star Hussein Ahmed Salah of Djibouti.

American Samoa, Angola, Belize, (the People's Republic of) China, Fiji, Guam, Guinea, the Maldives, Niger, Rwanda, and the Solomon Islands each made their first appearance in Olympic men's marathons.