The purpose of the study was to investigate the possible effect of an environmental organochlorine, dichlorodiphenyldichloroethylene (p.p'-), on male fertility assessed by main sperm variables, conducted through a case-control study on young men attending the andrology laboratory in the context of infertility investigation in the couple. Blood and semen samples were obtained from 73 young men considered as fertile based on semen analysis (controls) and 82 classified as subfertile or unfertile (cases). Standard clinical analysis of semen was performed and identification and quantification of p,p'-DDE in serum and in seminal plasma were done by gas chromatography. No p,p'-DDE was detected in the seminal plasma of either group. Blood concentration of pp'-DDE in both groups was very low and did not differ between cases and controls; however, blood samples were obtained from 23 mothers in the control group, and from 19 in the case group, and pp'-DDE serum level was significantly higher in the mothers of subfertile men. These data suggest that male infertility could be associated with exposure of the mothers to p,p'-DDE with deleterious effects restricted to intra-uterine life and thus undetected in blood or seminal plasma of subfertile men. (c) 2005 Elsevier Inc. All rights reserved.