Background: Single- dose ciprofloxacin is effective for the treatment of severe cholera in adults. We assessed whether single- dose ciprofloxacin would be as effective as 3- day, 12- dose erythromycin in achieving clinical cure in children with severe cholera. Methods: We did a randomised, open label, controlled trial in children age 2- 15 years with V cholerae O1 or O139 present in stool on dark- field microscopy. Children received either a single 20 mg/kg dose of ciprofloxacin (n = 90) or 12.5 mg/kg of erythromycin (n = 90) every 6 h for 3 days, and remained in hospital for 5 days. The primary outcome was clinical success of treatment, defined as cessation of watery stools within 48 h of start of drug treatment. Analysis was per protocol. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN00142272. Findings: Of 10 children randomised 162 completed the study. Treatment was clinically successful in 60% (47/78) of children treated with ciprofloxacin and in 55% (46/84) of those treated with erythromycin (difference 5% 95% CI - 10 to 21). Children receiving ciprofloxacin vomited less often (58% vs 74% ; difference 16% 2 to 30), had fewer stools (15 vs 21; 6 0 to 9), and less stool volume (152 vs 196 mL/kg; 43 mL/kg 13 to 87) than those receiving erythromycin. Bacteriological failure was more common in ciprofloxacin- treated patients (58% vs 30% ; 28% 13 to 43) than erythromycin- treated patients. Interpretation: Single- dose ciprofloxacin achieves clinical outcomes similar to, or better than, those achieved with 12- dose erythromycin treatment in childhood cholera, but is less effective in eradicating V cholerae from stool. Background: Single-dose ciprofloxacin is effective for the treatment of severe cholera in adults. Werate whether single-dose ciprofloxacin would be as effective as 3- day, 12-dose erythromycin in achieving clinical cure in children with severe cholera. Methods: We did a randomized, open label, controlled trial in children age 2- 15 years with V cholerae O1 or O139 present in stool on dark- field microscopy. Children received either a single 20 mg / kg dose of ciprofloxacin (n = 90) or 12.5 mg / kg of erythromycin (n = 90) every 6 h for 3 days, and remained in hospital for 5 days. The primary outcome was clinical success of treatment, defined as cessation of watery stools within 48 h of start of drug treatment. The study was registered as an International Standard Randomized Controlled Trial, number ISRCTN00142272. Findings: Of 10 children randomized 162 completed the study. Treatment was clinically successful in 60% (47/78) of children treated with ciprof loxacin and in 55% (46/84) of those treated with erythromycin (difference 5% 95% CI - 10 to 21). Children receiving ciprofloxacin vomited less often (58% vs 74%; difference 16% 2 to 30), had fewer stools (15 vs 21; 6 0 to 9), and less stool volume (152 vs 196 mL / kg; 43 mL / kg 13 to 87) than those receiving erythromycin. Bacteriological failure was more common in ciprofloxacin-treated patients % vs 30%; 28% 13 to 43) than erythromycin-treated patients. Interpretation: Single-dose ciprofloxacin achieves clinical outcomes similar to, or better than, those achieved with 12-dose erythromycin treatment in childhood cholera, but is less effective in eradicating V cholerae from stool.