| St. Louiscon, the 27th World Science Fiction Convention | |
| Dates: | 28 August–1 September 1969 |
| Filing: | non-profit |
| Attendance: | 1,534 |
The 27th World Science Fiction Convention (Worldcon), also known as St. Louiscon, was held on 28 August–1 September 1969 at the Chase Park Plaza Hotel in St. Louis, Missouri, United States.
The chairpersons were Ray Fisher and Joyce Fisher. The supporting organization was OSFA, the Ozark Science Fiction Association.
Attendance was 1,534, out of over 2,000 paid memberships.