Between February 1992 and January 1993 different Campylobacter spp. were isolated from 86 (13.7%) of 630 patients with diarrhoea at Tikur Anbessa and Ethio-Swedish Children's Hospital, Addis Ababa, Ethiopia. In the same study population, Shigella spp. were found in 11.7% and Salmonella spp. in 3.8%. Campylobacter spp. were found in all age groups, but the majority were isolated from children less than five years of age (68.6%). Only 2 (0.9%) of 220 controls had campylobacter in their stools. Of the campylobacters that were differentiated at species level, Campylobacter jejuni accounted for 82.4% and Campylobacter coli for 17.6% of the isolates. Yersinia enterocolitica was not isolated from any tested stool specimen. More patients (53.1%) presented for investigation of diarrhoea during the months of April through July than during other parts of the year but there was no significant difference in the frequency of isolation of the three enteric pathogens studied during this period as compared to other months of the year. In 12 of the patients infected with Campylobacter spp., Shigella spp. or Salmonella spp. was concomitantly isolated from their stools. The most common symptoms and signs in both adults and children were watery diarrhoea in 82.4%, low grade fever in 78.4% and frequent vomiting in 45.9%. Dehydration ranging from mild to severe was observed in 25.4% of the 55 children with campylobacter infections. Of the 55 children 67.2% had signs of malnutrition and most of them (47.2%) were underweight. This study indicates that Campylobacter spp. are an important cause of diarrhoea both in adults and children in Addis Ababa, and should be considered routinely in the diagnosis of patients with diarrhoea.