The use of nicotine through smoking remains a serious health problem. It has been associated with reduced fertility (Oyeyipo et al, 2011), although the mechanism responsible is still unclear. The present study was designed to investigate the effects of nicotine administration on male reproductive hormones in male albino rats. Forty male rats weighing between 200-230g (8-10 weeks) were divided equally into five groups and treated orally for thirty days. Group I, which served as the control received 0.2ml / kg normal saline, Group II and III received 0.5mg/kg (low dose) and 1.0mg/kg (High dose) body weight of nicotine respectively. The fourth and fifth groups were gavaged with 0.5mg/kg and 1.0mg/kg body weight of nicotine but were left untreated for another 30 days. These groups served as the recovery groups. At the end of the experimental period, animals were anaesthetized with 1.9% ether and blood was collected through cardiac puncture. Serum was analysed for testosterone, luteinizing hormone (LH), follicle stimulating hormones (FSH) and prolactin using radioimmunoassay. Values were expressed as mean ± S.E.M compared by ANOVA. Results showed that nicotine administration significantly decreased (p<0.05) testosterone in the low and high treated groups (3.46 ±0.16 ng /ml; 2.16 ± 0.18 ng /ml) and FSH (0.97 ±0.06 mIU/ml) in the high dose treated group when compared with the control group (4.94 ± 0.18; 2.01 ± 0.14) respectively. There was a significant increase (p<0.05) in mean LH (3.49 ± 0.20 mIU/ml) and mean prolactin level (8.10 ±0.32 IU/ml) in the high dose treated group when compared with the control (1.68 ±0.08 mIU/ml; 4.23 ± 0.26 mIU/ml) respectively. However, the values of the recovery groups were comparable with the control. Thus, these findings suggest that nicotine administration is associated with distorted reproductive hormones in male rats although ameliorated by nicotine cessation. It is plausible that the decreased testosterone level is associated with testicular dysfunction rather than a pituitary disorder.