BACKGROUND: The clinical efficacy and safety of a low-sodium hypotonic oral rehydration solution (LSORS) was compared in a pilot study with that of a standard World Health Organization oral rehydration solution (STORS) in young children with acute diarrhea. METHODS: One hundred and seventeen boys aged 3 to 18 months with acute diarrhea were randomly assigned to groups and received low-sodium (sodium 28 mmol/L) hypotonic oral rehydration solution and standard oral rehydration solution (sodium 90 mmol/L). Outcomes of therapy such as stool volume, duration of diarrhea and fluid intake were recorded at 24 hours, 48 hours, and the discontinuation of disease. Serum electrolytes levels were calculated before and after therapy. RESULTS: The stool output (gm/kg) in the first 24 hours was 69.2 +/- 38.5 in the LSORS group versus 105 +/- 39.8 in the STORS group (p < 0.05), while the total stool output during the 48-hour period was 151.4 +/- 68.9 in the LSORS group versus 232 +/- 97.3 in the STORS group (p < 0.05). No significant (p > 0.05) reduction in duration of diarrhea was noted (72.3 +/- 25.5 hours versus 69.8 +/- 29.4 hours). Four patients in the LSORS group and 7 patients in the STORS were classified as treatment failure. Forty-four (80%) achieved successful treatment in the LSORS group and 34 (56.7%) in the STORS group (p = 0.07). CONCLUSION: LSORS is as safe as STORS in treating young children with acute gastroenteritis. No evidence of hyponatremia was found after patient received LSORS. LSORS afforded more efficacious therapy than STORS.