In America and many European countries, prostate cancer is the most common cancer and the second leading cause of cancer death in men. Among 10-30% of all the men older than 50 years of age, a silent microscopic form of prostate cancer may be harbored. This high rate is similar throughout the world. However, few epidemiologic studies of prostate cancer have implicated its risk factors. A 1:1 matched case-control study looked into risk factors of prostate cancer. A total number of 102 cases of prostate cancer and 102 controls were surveyed. The results showed that high body mass index, history of urinary diseases, coitus frequency > 3 times per week, hormone drug use, and number of children > 3 are identified as risk factors of prostate cancer statistically, but physical labor, exercise, and age of first nocturnal emission > 18 are protective factors of prostate cancer.