An epidemiological study was undertaken to investigate an outbreak of cholera in Delhi Cantonment during May 1991. The study design was a hybrid design using a retrospective Case-Control method superimposed on a population based cross-sectional approach. A total of 9 cases of cholera, confirmed in the laboratory as Vibrio cholerae, 0-1, Eltor, Ogawa were identified using population based survey and compared with 33 controls from the same source population. The overall Incidence rate was 0.71% and showed a significant rising trend with age. There was no morality. Assessment of water supply, sanitary conditions of cook houses and disposal system of night soil could not provide any clue to the source of infection. Subsequently, all the food handlers were subjected to rectal swab examination. Two of them, working in the same messes from where cases had occurred, were found positive for Vibrio cholerae (0-1, Eltor, Ogawa). Immediate control measures by way of isolation and treatment of carriers promptly abated the outbreak. Role of carriers in outbreak of cholera has been highlighted.