- Objective To compare the levels of interleukin (IL) 1 β , IL-6, tumor necrosis factor (TNF) α , and soluble TNF (sTNF) receptors types I and II, and IL-1 receptor antagonist in seminal plasma of fertile and infertile men. Design Prospective and comparative study. Setting Andrology clinic of a university hospital. Patients Four groups of normogonadotropic men: group 1, donors with proven fertility (controls, n = 15); group 2, azoospermic men (n = 12); group 3, infertile men with oligoteratoasthenospermia (n = 20); and 11 men with oligoteratoasthenospermia and genital infection (n = 11). Interventions None. Main Outcome Measure Measurement of cytokines and cytokine-soluble receptors in the semen by specific commercial kits. Results The levels of IL-1 β , TNF- α , and IL-6 were similar in seminal plasma of controls and infertile men. The mean level of sTNF-I receptor in the seminal plasma of group 4 was 2.4 ± 0.2 ng/mL, which was significantly lower than observed in seminal plasma of group 1 (3.88 ± 0.5 ng/mL), the group 3 (4.1 ± 0.4 ng/mL), or group 2 (3.03 ± 0.35 ng/mL). The soluble receptor of TNF-II could not be detected in any group. Interleukin 1ra was 120 ± 10 pg/mL in seminal plasma of group 1, but increased levels were detected in group 2 (420 ± 180 pg/mL), group 3 (480 ± 90 pg/mL), and even higher (760 ± 120 ng/mL) in group 4 patients. Conclusions During genital infection cytokines and various soluble receptors of immunoregulatory cytokines are expressed distinctly in seminal plasma. These factors also may be involved in the regulation of sperm cell functions and thus may affect male fertility. Our results may indicate local production of these factors in the secondary sex glands, independently of spermatogenesis.