Between 23 August and 15 December 1990 an epidemic of cholera affected Mozambican refugees in Malawi causing 1931 cases (attack rate=2·4%); 86% of patients had arrived in Malawi <3 months before illness onset. There were 68 deaths (case-fatality rate=3·5%); most deaths (63%) occurred within 24 h of hospital admission which may have indicated delayed presentation to health facilities and inadequate early rehydration. Mortality was higher in children <4 years old and febrile deaths may have been associated with prolonged IV use. Significant risk factors for illness (P<0·05) in two case-control studies included drinking river water (odds ratio [OR]=3·0); placing hands into stored household drinking water (OR=6·0); and among those without adequate firewood to reheat food, eating leftover cooked peas (OR=8·0). Toxigenic V. cholerae O1, serotype Inaba, was isolated from patients and stored household water. The rapidity with which newly arrived refugees became infected precluded effective use of a cholera vaccine to prevent cases unless vaccination had occurred immediately upon camp arrival. Improved access to treatment and care of paediatric patients, and increased use of oral rehydration therapy, could decrease mortality. Preventing future cholera outbreaks in Africa will depend on interrupting both waterborne and foodborne transmission of this pathogen.