The meiotic study of spermatocytes may provide important information for the underline cause of male infertility, many of which originate from meiotic errors, especially during early stages of meiosis. Spermatocytes from nine infertile men and one vesectomied man, age 23 to 43 years, were analyzed. All, except one, had normal levels of gonadotropic and sex hormones, and regular size of testes. One patient had no meiosis. Four showed azoospermia and 5 were oligospermia. Abnormal meiotic behaviors including pairing irregularities such as defective pairing of sex chromosomes, absence of sex vesicle, complete or partial nonpaired homologous chromosomes at pachytene and DK/MI, univalents ad MII, and complete or partial spermatic arrest were observed. Supernumerary chromosome was detected in one patient. The vasectomied patient also displayed spermatic arrest with few meiotic errors in the early stages. The results indicated that infertilemen could reveal different underline cause with unique meiotic abnormalities.