The pathophysiological significance of seminal cytokines in sperm function is still controversial. We determined the repertoire of cytokines in seminal plasma obtained from men with or without abnormalities in semen and assessed the pathophysiological significance of seminal cytokines. After conventional analysis of semen samples obtained from 86 men, levels of seminal cytokines (interleukin [IL]-1alpha, IL-2, IL-4, IL-6, IL-8, tumor necrosis factor-alpha [TNF-alpha], interferon-gamma, granulocyte colony-stimulating factor [G-CSF], macrophage CFS [M-CSF]) and granulocyte elastase were measured by an enzyme-linked immunosorbent assay. Leukocytospermia was defined as seminal plasma, which has > or =1000 ng/ml granulocyte elastase. Leukocytospermia was found in nine of 62 of the subjects in the normozoospermic group but in none of the 24 subjects showing abnormal sperm parameters (azoospermia, n=5; oligozoospermia, n=4; asthenozoospermia, n=15). The IL-8 level in the leukocytospermic group was significantly higher than those in the normal and oligozoospermic groups. IL-1alpha and TNF-alpha levels in the leukocytospermic group were significantly higher than those in the normal and asthenozoospermic groups. Although the G-CSF level in the leukocytospermic group was significantly higher than that in the normal group, high levels of M-CSF were detected in all groups. The IL-8 level was strongly correlated with IL-1alpha (r=0.935, P<0.0001) and G-CSF (r=0.916, P<0.0001) levels. Cytokines detected in seminal plasma are associated with the pathogenesis of leukocytospermia but not with the pathogenesis of asthenozoospermia and oligozoospermia.