OBJECTIVE: To assess the prevalence of diabetes and IGT in the urban adult Brazilian population. RESEARCH DESIGN AND METHODS: We used a two-stage, multicenter, cross-sectional survey in a random sample of 21,847 individuals aged 30–69 yr from nine large cities. Subjects were first screened by FCG. All positive screenees (FCG ≥ 5.6 mM/L) and every sixth consecutive negative screenee were administered a 75 g OGTT and classified as diabetic, IGT, or normal (nondiabetic) according to WHO recommendations. OGTT findings from the negative screenees were extrapolated to all negative screenees after adjustments for potential biases. RESULTS: The overall rates were 7.6 and 7.8% for diabetes and IGT, respectively. Men (7.5%) and women (7.6%) had similar rates of diabetes. Similar rates resulted with whites (7.8%) and nonwhites (7.3%). Diabetes prevalence increased from 2.7% in the 30–39-yr age-group to 17.4% in the 60–69-yr age-group. Diabetes was more prevalent among less educated people, but this difference disappeared after adjusting for age. Family history of diabetes was associated with a twofold increase in diabetes prevalence (12.5 vs. 5.8%); the same increase occurred with obesity (11.6 vs. 5.2%). Undiagnosed diabetes accounted for 46% of the total prevalence. Among previously diagnosed cases, 22.3% were not under treatment, 7.9% were on insulin, 40.7% were on oral agents, and 29.1% were on dietary treatment only. Self-reported diabetes prevalence was 0.1, 3.2, and 11.6% in the age groups < 30, 30–69, and > 70 yr, respectively. CONCLUSIONS: The prevalence of diabetes in Brazil is comparable with that of more developed countries, where it is considered a major health problem.