During a conference on diarrhoeal diseases in Tanzania in 1984, 19 participants representing 16 countries in Africa gave the formulae for oral rehydration solutions therapy (ORS) which they recommended or instructed for home use in their own countries. There were gross variations in recommended quantities of sugar, salt and water. Theoretical calculations indicated that the glucose concentration ranged from 29 to 174 mmol/l (recommended 30-112 mmol/l) and that of sodium from 9 to 116 mmol/l (recommended 30-80 mmol/l). It is very important that countries should ensure that the recommendations for making up oral rehydration solutions be standardized, otherwise dangerous or ineffectual concentrations of salt and sugar solutions may be used for rehydrating children.