Several previous studies have demonstrated an increased prevalence of gout in New Zealand Maoris. The aetiology of the hyperuricaemia and its effect on morbidity, apart from gout, are unknown. A survey of 115 Maori men of working age revealed a history of gout in 10 (8%) and asymptomatic hyperuricaemia in 26 (23%). The relationship of hyperuricaemia with obesity was confirmed. Alcohol did not make an obvious contribution to the prevalence of hyperuricaemia. Hypertension was more common and creatinine clearance lower amongst those with gout, but not significantly so. The frequency of hypertension and mean creatinine clearance were similar to that seen in asymptomatic hyperuricaemia and normouricaemia. Urate clearance was lower in the gouty and hyperuricaemic subjects. The normouricaemic Maoris had a reduced fractional urate clearance compared with normal men elsewhere. They also excreted a relatively small proportion of hydrogen as ammonium. Both these features are characteristic of gout, and suggest that the Maoris' susceptibility to hyperuricaemia has a renal mechanism. Obesity is common amongst the Maoris and accentuates their natural tendency to hyperuricaemia.