OBJECTIVE To study the relationship between the testis volume and types of spermatogenic cells derived from testicular biopsy in patients with azoospermia or cryptozoospermia. METHODS We collected testicular pathological biopsies from 492 infertile patients with azoospermia or cryptozoospermia reported in our hospital, classified them according to the testicular histological classification methods in WHO Manual for Standardized Investigation, Diagnosis and Management of the Infertile Male, and analyzed the relationship of the testis volume with the results of semen analyses and testicular histology. RESULTS Of the 492 cases, 90.5% (445/492) were azoospermia and 9.5% (47/492) cryptozoospermia; mature spermatozoa were present in the seminiferous tubules in 17.9% (88/492) but absent in 42.9% (211/492), and Sertoli cell-only syndrome indicated in 39.2% (193/492); the testis volume was < or = 10 ml in 38.6% (190/492) and < or = 5 ml in 7.9% (39/492). Cryptozoospermia was detected in 14.8% (13/88) of those with mature spermatozoa in the seminiferous tubules, in 11.4% (24/211) of those without, and in 5.2% (10/193) of those with Sertoli cell-only syndrome, with a significantly lower rate in the latter group than in the former two (P < 0.05). CONCLUSIONS Spermatogenesis of the testis may be focal and difficult to be completely reflected by a single testicular biopsy, and it may exist even if the testis volume is significantly below the reference value. The indications for testicular biopsy should not be improperly expanded. The WHO testicular histological classification methods have provided a convenient and effective guidance for further clinical examinations and establishment of a protocol.