The role of cell-mediated immunity in the aetiopathogenesis of male infertility is far from being defined. The cytochemokine interleukin-8 (IL-8) has a key role in T-cell mediated immune responses. The aim of this study was to confirm the presence of IL-8 in human seminal plasma, to show differences between IL-8 concentrations in fertile and infertile subjects, and to show the potential relationship between IL-8 amounts in semen and spermiogram parameters. IL-8 levels were determined in the seminal plasma of 77 men divided as follows: (a) into seven groups according to the aetiological diagnosis of fertility and (b) into two groups on the basis of a normal or abnormal spermiogram. The mean value of IL-8 in the seminal plasma was 31.5 times higher than the upper limit in normal serum. There is a borderline statistical significant difference among the means of the various groups (P < 0.051). The Tukey's HSD test for multiple comparisons indicated no two groups as being significantly different, whereas the less conservative test LSD showed significant differences between the group with infection and groups with normal controls, Klinefelter's syndrome, mumps orchitis, cryptorchidism, or varicocele. There was no significant difference in IL-8 levels between men with normal and those with abnormal spermiograms. Furthermore, there was no correlation between IL-8 levels and the variables of the spermiogram. Even though the conclusions of this study have to be tempered by the sample size, IL-8 concentration in seminal plasma may be considered as a potential marker for the diagnosis of male accessory gland infection.