1. Patients with sickle-cell anaemia were unable to increase free water reabsorption (TcH2O) in response to intravenous hypertonic sodium chloride solution.
2. Ethacrynic acid caused a brisk natriuresis in patients with sickle-cell anaemia but fractional sodium excretion was lower in these patients.
3. These findings could be explained by abnormal function of the loop of Henle.