This study was conducted to confirm the presence of IL-11 in human seminal plasma, to show eventual differences between IL-11 concentration in fertile and infertile subjects, and to show if urogenital infection is a factor determining its elevation. Seminal plasma from 93 men obtained by masturbation was examined for the presence of IL-11 using an IL-11-specific sandwich ELISA. Semen samples were obtained from 93 men divided (1) into seven groups according to the etiological diagnosis of fertility and, (2) into two groups on the basis of normal or abnormal spermio-gram. The correlation of amount of IL-11 in seminal plasma with some spermiogram parameters was statistically evaluated. There was a statistically significant difference between the groups (p = 0.0007) due to group infection of accessory genital glands, which presents the highest mean rank value as compared to all other groups. The group normal spermiogram had a mean value for IL-11 of 51.83, while the abnormal spermiogram was 66.30. This difference is not statistically significant (p > 0.05). There was no correlation between IL-11 levels and the variables of the spermiogram. These findings demonstrate IL-11 to be in seminal plasma, and elevated IL-11 levels are detected in infertile patients with urogenital infections.