OBJECTIVE To examine the incidence and determinants of elevated urinary albumin excretion in Pima Indians with non-insulin-dependent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS The incidence of elevated urinary albumin excretion (≥30 mg albumin/g creatinine) and its relationship with baseline characteristics was determined in 456 Pima Indians ≥15 years old with NIDDM who were followed for up to 11.6 years (median 4.7 years). RESULTS Of these 456 subjects, 192 (42%; 58 men, 134 women) developed elevated urinary albumin excretion, 172 of whom (90%) were within the microalbu-minuric range (30–299 mg/g). The incidence of elevated urinary albumin excretion was related to retinopathy, type of diabetes treatment, longer duration of diabetes, lower body mass index, and higher values of mean arterial pressure, HbA1, and fasting and 2-h postload plasma glucose concentration at the baseline examination, but not to sex. A relationship with cholesterol was found in durations of diabetes of ≥10 years. The cumulative incidence of elevated albumin excretion was 17% after 5 years of NIDDM. CONCLUSIONS The incidence of elevated urinary albumin excretion in Pima Indians with NIDDM is at least as high as that reported previously in insulin-dependent diabetes mellitus, and its major determinants are the same as those shown previously to predict the development of more advanced renal disease in this population.