OBJECTIVE To investigate whether testicular cytology by fine needle aspiration (FNA) may be considered a diagnostic parameter in the evaluation of the azoospermic subject. METHODS Cytologic smears were obtained using a 23-G needle, stained with May-Grünwald-Giemsa stain and examined under a light Orthoplan microscope (Wild, Leitz, Germany) for qualitative and quantitative analysis. METHODS Fifty-four azoospermic patients were analyzed, and the findings were compared with those obtained from 40 normozoospermic infertile subjects used as controls. METHODS Two hundred spermatogenic cells were counted and classified at the various steps of spermatogenesis. Spermatic index and Sertoli index provided further elucidations and more comprehensible results. RESULTS No sign of traumatization was observed. Cytologic analysis was proved to have high statistical reproducibility (P less than 0.01 for spermatogonia and secondary spermatocytes and P less than 0.001 for the other cell types, when compared between differential counts) and permitted identification of different situations associated with azoospermia: Sertoli cell-only syndrome, germ depopulation (hypospermatogenesis), spermatogonial arrest, spermatidic arrest, and obstructive azoospermia. These findings agreed with clinical and hormonal parameters and with the results of bilateral surgical biopsies, when performed. CONCLUSIONS The results support use of FNA of the testis as a noninvasive diagnostic parameter for the assessment of azoospermic subjects.