Purpose The incidence of prostate cancer in Saudi Arabia has been reported to be low at 1.4 to 2.1/100,000 person-years. We prospectively evaluated the true incidence of this disease and its association with dietary factors. Materials and Methods From 1994 to 1997 inclusive Saudi men older than 50 years treated at our institution for various presenting symptoms and diseases were randomly selected from various departments. They were examined prospectively with digital rectal examination, and total and free prostate specific antigen measurement. Transrectal ultrasound and prostatic biopsy were performed when either test was abnormal. Nutrition questionnaires and detailed interviews with a nutritionist were completed to assess the type of diet, and amount of saturated and polyunsaturated fat consumption of patients with prostatic carcinoma and controls. Results For the 2,270 Saudi men screened we noted an incidence of 3.1/100,000 person-years. Our nutritional survey revealed that recent fat consumption was greater than 120 gm. per person daily, of which about 40% was from meat and dairy products. Saturated fat comprised about 50% of the total fat intake. There was no difference in the amount of fat in the diet of men with and without prostatic carcinoma. Conclusions The incidence of prostatic carcinoma in the Kingdom of Saudi Arabia is low despite a high saturated fat diet in recent years. This finding contradicts most western clinical studies, which indicate a positive association of a high fat diet with prostatic carcinoma.