To quantify the consequences of asymptomatic hyperuricemia, this study examined rates for a first episode of gouty arthritis based on 30,147 human-years of prospective observation. A cohort of 2,046 initially healthy men in the Normative Aging Study was followed for 14.9 years with serial examinations and measurement of urate levels. With prior serum urate levels of 9 mg/dl or more, the annual incidence rate of gouty arthritis was 4.9 percent, compared with 0.5 percent for urate levels of 7.0 to 8.9 mg/dl and 0.1 percent for urate levels below 7.0 mg/dl. With urate levels of 9 mg/dl or higher, cumulative incidence of gouty arthritis reached 22 percent after five years. Incidence rates were three times higher for hypertensive patients than for normotensive patients (p less than 0.01). The strongest predictors of gout in a proportional hazards model were age, body mass index, hypertension, and cholesterol level, and alcohol intake. When the serum urate level became a factor in the model, none of these variables retained independent predictive power. At the final examination, only 0.7 percent of participants had a serum creatinine level of 2.0 mg/dl or more, with no evidence of renal deterioration attributable to hyperuricemia. These data support conservative management of asymptomatic hyperuricemia.