ABSTRACT. An oral rehydration solution (ORS) containing 60 mmol/l of Na'(ORS60) was compared in a randomized trial with the ORS of WHO formula (Na+ 90 mmol/l = ORS90) for the treatment of diarrhoeal dehydration in 66 hospitalized infants aged 3 to 34 months. The infants had a 5±3 % dehydration, and received within 6–10 hours 76±32 ml/kg of ORS60 or 74±41 ml/kg of ORS90 corresponding to a sodium input of 4.6±1.9 mmol/kg and 6.6±3.7 mmol/kg, respectively. Both treatments were found adequate and equally effective for the correction of dehydration and sodium deficit. The same ORSM was also compared to a commercial low sodium glucose-electrolyte solution (sodium 35 mmol/l, glucose 3.5 g/1) for ambulatory treatment of acute diarrhoea in infants. Satisfactory rehydration was achieved within 6 hours in 19 of 23 infants receiving ORS60 as opposed to 6 of 18 infants receiving the commercial solution (p<0.001); the poor result with the latter was in most cases attributed to a refusal by the infant to consume the sweetish solution. It is concluded that ORS60 is suitable for the treatment of isotonic diarrhoeal dehydration in hospitalized children as well as outpatients.