This study evaluated how many patients with azoospermia might have fertility potential using assisted conception techniques. A total of 102 male patients with azoospermia were included in the study. Thirteen patients had sex chromosomal abnormalities. Testicular biopsy performed in the other 89 patients showed incomplete spermatogenesis in 47 of them whereas 42 had complete spermatogenesis. In the latter 42 patients, distal vasography demonstrated bilateral obstruction of the excurrent ducts in 14 patients whereas no distal obstruction of the ducts was found in 28. The 89 patients were divided into three groups according to the findings of testicular biopsy and distal vasography. In the 14 patients with both complete spermatogenesis and distal obstruction of the excurrent ducts, surgical procedures are applicable. The pathogenesis of the 28 patients with complete spermatogenesis but without distal obstruction of the ducts should be clarified for further treatment.