en Original Article Original Article <strong>Backgrand:</strong> Cotinine (COT) is a major degradation product of nicotine (NIC). The participation of leptin in female reproduction is well-established, but any role in male reproductive function is at the best tenuous.<br> <strong>Objective:</strong> The aim of this study was to evaluate the in-vitro effects of nicotine, cotinine and leptin on sperm parameters in normal semen of non-smokers fertile men.<br> <strong>Materials and Methods:</strong> Ten healthy nonsmokers aged 25-40 years old were devided into 7 groups, Thier semens were divided into 7 aliquots. (A) was layered with basal solution 70 ng/ml NIC, (B) 35 &micro;g/ml NIC, (C) 300 ng/ml COT, (D) 200 &micro;g/ml COT, (E) 30 ng/ml leptin, (F) 300 ng/ml leptin respectively and (G) was layered with mHTF. After migration, the samples were examined at time 0, +1, +2, +4, +8, and + 24 h of incubation.<br> <strong>Results:</strong> These findings were obtained: sperm count: 75.66&plusmn;66.25x10 6 /ml, forward motility: 75.55&plusmn;14.80%, progress: 33.66&plusmn;13.01, VSL: 51.58&plusmn;6.99 &micro;m/s, VCL: 103.33&plusmn;14.52 &micro;m/s, ALH: 4.33&plusmn;0.77 &micro;m, BCF: 25.60&plusmn;2.97 HZ, STR: 79.33&plusmn;8.04 %, LIN: 52.55&plusmn;10.52 %, ELO: 74.22 &plusmn; 12.76 % and ARE: 3.04 &plusmn; 1.50 u/sq. The parameters were similar before 8 hr and were being decreased after that.<br> <strong>Conclusion:</strong> According to the results. nicotin and cotinin have negative effects on the sperm parameters but despite the positive effect of leptin, there is no correlation between leptin concentration in semen and its physical characteristics. Nicotine, Cotinine, Leptin, Sperm parameters 157 0 http://ijrm.ir/browse.php?a_code=A-10-549-257&slc_lang=en&sid=1 Seyed Gholam Ali Jorsaraei alijorsara@yahoo.com Yes Fateme Zahra Fertility and Infertility Reaserch Center, Babol University of Medical Sciences, Babol, Iran Hiroaki Shibahara No Department of Obstetrics and Gynecology, School of Medicine, Jichi Medical University, Tochigi, Japan Ayustawati No Department of Obstetrics and Gynecology, School of Medicine, Jichi Medical University, Tochigi, Japan Yuki Hirano No Department of Obstetrics and Gynecology, School of Medicine, Jichi Medical University, Tochigi, Japan Yasuko Shiraishi No Department of Obstetrics and Gynecology, School of Medicine, Jichi Medical University, Tochigi, Japan Ali khalatbari No Fateme Zahra Fertility and Infertility Reaserch Center, Babol University of Medical Sciences, Babol, Iran Yousofreza Yousofnia Pasha No Fateme Zahra Fertility and Infertility Reaserch Center, Babol University of Medical Sciences, Babol, Iran Mitsuaki Suzuki No Department of Obstetrics and Gynecology, School of Medicine, Jichi Medical University, Tochigi, Japan