An outbreak of Shiga bacillus (Shigella dysenteriae type 1) infection has been detected for the first time in South Africa. Forty-eight cases of this epidemic that presented to a referral hospital were clinically evaluated. Patients presented with dysentery from all age groups and 16 (33%) were admitted to hospital. There were two geographical regions where 32 (67%) of the patients resided. The isolates were demonstrated to be pathogenic by in vitro testing for invasion and toxin production, and were found to be resistant to first line antibiotics that have been used for the treatment of shigellosis i.e. ampicillin, cotrimoxazole, tetracycline and chloramphenicol. However, they were susceptible to nalidixic acid, ceftriaxone and ciprofloxacin. Urgent, public health measures are needed to prevent further spread of this epidemic.