From three fatal cases of diarrhoeal illness in Bangladesh, Yersinia species were isolated from tissues at post-mortem examination. One patient was infected with Y. enterocolitica serotype 0:7, 8 and two patients were infected with Y. intermedia. These patients were infected also with other enteric pathogens. These findings suggest that Yersinia may be important as pathogens in tropical diarrhoea and as co-pathogens in serious disease.