OBJECTIVE To evaluate the patterns of testicular cytology in men with primary infertility, to compare the morphologic patterns between the periods 1990-1995, immediately after Gulf War II, and 1997-2001 and to determine whether there is a correlation between hormonal profile, testicular volume and morphologic pattern. STUDY DESIGN Retrospective study of men with primary infertility. History, complete physical examination, hormonal assay and testicular ultrasound were evaluated. A total of 545 patients had samples for testicular cytology obtained from both testes. The patient's consent was obtained in all cases. Smears were interpreted under light microscopy after treatment with Diff-Quik. A total of 104 healthy, fertile subjects were used for comparison of the hormonal profile and testicular volume. RESULTS The mean (+/- SD) age was 28.66 +/- 4.36 years and duration of marriage 4.4 +/- 4.36 years. There were 11.2% patients with normal cytology, 55.8% with hypospermatogenesis, 28.4% with testicular atrophy, 2.9% with Sertoli cells only and 1.7% with maturation arrest. A significant increase in hypospermatogenesis and decrease in the Sertoli cell-only pattern were noted in 1997-2001 when compared with 1990-1995. The mean left testicular volume was 10.53 +/- 5.51 mL3 in the infertile group vs. 15.2 +/- 4.97 in the fertile group (p < 0.003); right testicular volume was 10.84 +/- 4.77 vs. 15.15 +/- 5.31 (p < 0.003). The hormonal profile revealed higher luteinizing hormone and follicle-stimulating hormone levels in the infertile group vs. control group (8.53 +/- 9.03 and 16.44 +/- 19.243 vs. 6.98 +/- 4.53 and 7.37 +/- 6.63, respectively [p < 0.001]). Free testosterone was higher in the fertile group (39.69 +/- 12.76 vs. 20.28 +/- 8.5 [p < 0.000]). CONCLUSION The majority of infertile males in our cohort had hypospermatogenesis; testicular atrophy was the next most common disorder. There was no major change in overall absolute numbers since the Gulf War. Testicular cytology by fine needle aspiration is a safe and well-tolerated complementary investigation for unexplained male infertility.