Polybrominated diphenyl ethers are known to be endocrine disruptors and may affect male reproduction. This exploratory study investigated semen parameters and serum thyroid hormones in relation to serum PBDE, PCBs and p-p' DDE in adult men.Fifty-two men were recruited in a fertility clinic. Semen counts were done for each participant. Serum thyroid hormone and PBDE, PCB and p-p' DDE levels were measured. Sociodemographic questionnaire were administered to each participant and all medical data were obtained from medical record.Semen mobility was negatively related to BDE-47, BDE-100 and ΣBDE. No relations were observed with other semen parameters. Thyroxin levels were negatively associated to serum BDE-47, BDE-99, ΣBDE and p-p' DDE and positively related to ΣPCB. No relations were observed between T3, TSH and any of the chemicals measured.These findings increased the evidence that PBDE may interfere with semen quality and thyroid status in general population.