To evaluate the efficacy of erythromycin and trimethoprim-sulphamethoxazole (TMP-SMX) in the treatment of cholera in children aged 1-8 years, a randomised clinical trial was conducted at a diarrhoea treatment centre in Bangladesh from December 1991 to June 1992. Fifteen children received erythromycin, 50 mg/kg per day, in four equally divided doses, 18 children received 10 mg/kg per day of trimethoprim and 50 mg/kg per day of sulphamethoxazole in two equally divided doses (12 hourly) for five days, and 15 children received no antibiotic; children in all three groups received intravenous cholera saline for severe dehydration and for mild to moderate dehydration, a rice-based oral rehydration solution. The mean stool volumes in mL/kg body weight in the two treatment groups were less than that of the control group, and there were no significant differences in stool volume among the two treatment groups. However, 67% of the children in the erythromycin group and 82% in the TMP-SMX group recovered within 72 hours compared to 33% in the control group (p < 0.01). Similarly, the bacteriological cures were 80% in the erythromycin group and 83% in the TMP-SMX group compared to only 27% in the control group (p < 0.001). These results confirm that both erythromycin and trimethoprim-sulphamethoxazole are effective antimicrobials in the treatment of cholera. These drugs are of value specially in younger children in whom tetracycline is contraindicated or when the infecting Vibrio cholerae are resistant to tetracycline.