Non-insulin-dependent diabetes mellitus (NIDDM) is a major clinical and public health problem in Kuwait. The objective of the study was to determine prevalence rates of NIDDM among a representative sample of the Kuwaiti adult population aged 20 and older in two out of five governorates and identify the associated risk factors for the disease. A total of 3003 subjects (1105 men and 1898 women) were interviewed and examined by the research team during the period September 1995 to June 1996. A specially designed questionnaire was completed and the physical examination included height, weight and blood pressure measurements. Fasting blood samples were withdrawn, centrifuged immediately and refrigerated. Interpretation of oral glucose tolerance tests were based on the World Health Organisation diagnostic criteria for diabetes mellitus (1985). The denominator used for computing the prevalence was obtained from the 1995 Kuwait census. The overall prevalence of NIDDM in this study was found to be 14.8% (14.7% in men, 14.8% in women). Diabetic subjects presented at a relatively young age, prevalence rate in the age group 20-39 was 5.7% (95% confidence interval, 4.4-7.0) and in the age group 40-59 was 18.3% (95% confidence interval, 16.1-20.6). Obesity was found to be a significant risk factor, P < 0.001. The strong association of family history of NIDDM (adjusted odds ratio = 1.80, P < 0.001) suggests a genetic component. Hypertension was markedly associated with NIDDM and IGT (P < 0.001). With the demographic transition which already started among the Kuwaiti population and if the prevalence of NIDDM remains the same, aging of the population will contribute to even more upward trends in prevalence of abnormal glucose tolerance with its serious impact on morbidity and mortality among the Kuwaiti population. The strong association between hypertension and NIDDM may suggest a common approach to the prevention and control of these two conditions.