Hyperuricaemia is a common complication of diuretic use in man and its simple elimination as a side effect would be an advantage. The finding that the indanone diuretic, MK-196, was actually uricosuric in the chimpanzee (Fanelli et alii, 1974), was of potential importance to human therapeutics. Initial studies had confirmed that a 10 mg dose was diuretic in healthy volunteers but had very little effect upon the serum urate concentration. An important question therefore was to decide whether larger doses of the drug would have a greater uricosuric effect without a corresponding increase in the natriuretic or kaluretic effects.