Serum testosterone, seminal fructose, citric acid, and prolactin were measured in 33 men attending an infertility clinic. Seminal samples were assessed for leucocytes using the peroxidase stain technique and were grouped as leucocytospermics or not. Corrected fructose was calculated from actual fructose concentration. The objective of the study was to use the combined measurement of serum levels of testosterone and levels of corrected seminal fructose as a test to determine the presence or absence of an obstructive process by inflammation at the reproductive tract. Seminal fructose and corrected fructose were lower in subjects with leucocytospermia, whereas serum testosterone, seminal prolactin, and citric acid were not different between groups with and without leucocytospermia. In 61.5% of the samples with leucocytospermia were observed both low corrected seminal fructose and normal serum testosterone levels, indicating an obstructive process. Seminal prolactin levels in leucocytospermic subjects were more associated with citric acid concentration than with corrected fructose, suggesting that prolactin is also secreted by the prostate. In summary, the data demonstrated that when leucocytospermia, normal serum testosterone concentration, and low corrected seminal fructose level are present, an obstructive process of the seminal vesicles may be suspected. © 1994 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.