OBJECTIVES: The present study aimed to determine the prevalence and etiology of erectile dysfunction in Saudi type 2 diabetic patients. PATIENTS AND METHODS: 429 Saudi type 2 diabetic male patients aged more than 30 years were recruited. Total and bio-available serum testosterone, sex hormone binding globulin and free testosterone levels were measured by ELISA-IBL GMBH Germany. RESULTS: 47 ( 12.6%) subjects had hypogonadism with total testosterone < 8 nmol/l and 109 (29.3%) had possible hypogonadism with a total testosterone between 8 and 12 nmol/l. Similarly, using bioavailable levels, 30 (8%) men had overt hypogonadism with bioavailable testosterone < 2.5 nmol/l and 89 (33.9%) men had possible hypogonadism with bioavailable testosterone between 2.5-4 nmol/l; while 266 (71.6%) patients with free testosterone < 0.255 nmol/l had hypogonadism. BMI and waist circumference were both significantly negatively correlated with testosterone levels in Saudi type 2 diabetic men. CONCLUSIONS: Testosterone levels are frequently low in Saudi men with type 2 diabetes and majority of these patients have symptoms of hypogonadism. The prevalence of erectile dysfunction (ED) was 86.7% in diabetic men with low testosterone level of 8-12 nmol/L. Obesity is an associated factor with low testosterone levels and ED in Saudi type 2 diabetic patients.