An outbreak of dysentery due to Shigella dysenteriae type 1 occurred in a chronic care psychiatric institution in Durban, South Africa. Of the 10 patients who developed dysentery, 4 (40%) died. S. dysenteriae type 1 was isolated from stool samples from two of the four patients tested and ribotyping showed that these isolates were identical but differed from other community acquired strains. The isolates were resistant to ampicillin, chloramphenicol, tetracycline and co-trimoxazole. Infection control measures including isolation, cohort nursing and strict hand disinfection resulted in rapid control of the outbreak.