As one of large outbreaks of cholera-like illness in the Indian subcontinent, Calcutta and its neighbouring areas experienced an unprecedented epidemic due to a new strain of V. cholerae non-01, designated as V. cholerae 0139 Bengal, since January 1993. This epidemic predominantly affected the adult population of Calcutta as evidenced by the hospitalization of more adults at the Infectious Disease Hospital, Calcutta (IDH), which bore the main brunt of the epidemic in and around Calcutta. During the peak of the epidemic about 180 to 300 diarrhoea patients were admitted daily at the IDH. Of the 807 patients screened, 407 were positive for V. cholerae 0139 and majority (82.8%) of the cases were > 10 yr of age. Severe dehydration was recorded in 85.5 per cent of the cases.