Objective: The reproductive system is affected by both epilepsy and antiepileptic drugs. Reduced fertility associated with usage of antiepileptic drugs has been reported in both men and women with epilepsy. This study was conducted to assess the effects of long-term use of pregabalin on reproductive endocrine hormones and testicular morphology in adult male rats. Material and Methods: Thirty adult male Wistar rats were included in the study and were divided into two groups. The treatment group (n= 20) was fed orally through a gastric tube with pregabalin twice daily for 60 days. The pregabalin mixture was prepared by dissolving pregabalin in distilled water. The treatment group rats received 40 mg/kg pregabalin solution twice daily. Control group animals received only distilled water. The results were analyzed using the Mann-Whitney U test. Results: Pregabalin caused a slight decrease in body weight in the experimental group when baseline and final body weights were compared. Serum free testosterone levels were decreased in the pregabalin-treated group when compared with the control group; this difference was statistically significant. There was no significant difference between the pregabalin-treated rats and the rats receiving control solution regarding follicule stimulating hormone (FSH), luteinizing hormone (LH) and sex hormone binding globulin (SHBG) levels. Serum biochemical markers including alanine aminotransferase, aspartate aminotransferase, total protein, triglycerides and cholesterol were within normal ranges. Seminiferous tubule epithelium thickness was increased and tubule diameters were decreased in the treatment group compared to the control group. Conclusion: We suggest that the Leydig cells with a primary function of secreting testosterone are mildly affected by pregabalin.