The sodium contents of six differently prepared oral rehydration solutions (ORS) were measured. A total of 452 solutions were prepared in our gastro-enteritis unit. The finger-pinch-and-cup method produced sodium values that were too high and too variable. The most acceptable sodium level was achieved using half a 5 ml medicine teaspoon or 1 level common household teaspoon of salt in 1 litre of water. Half a commonly available household teaspoon of salt caused sodium levels to be low but still acceptable and safe. We recommend that half a teaspoon of salt in 1 litre of water be used when preparing an ORS.