Background: Relationship between obesity and male subfertility is a matter of controversial. Objective: To clarify relationship between obesity and male subfertility as well as confirm the relationship between BMI and quality of semen parameters. Methods: Study is observational cross-sectional, conducted in Department of Dermatology, Venereology and Andrology, Assiut University Hospital, between May and September 2015. Two hundred twenty males met our inclusion criteria were enrolled. Semen analysis was done to volunteers for follow up of their reproductive health after getting their consent. History taking, general and local genital examinations were done: participants were divided into 3 groups, group (I) normal weight (42) , (II) overweight (104) , (III) obese (94). Results: Mean BMI was 29.5 ± 6.2, semen volume was decreased from 3.3 ± 1.2 in normal weight to 2.9 ± 1.45 & 2.56 ± 1.4 in overweight and obese (P= 0.02). Similar findings were reported in sperm concentration and count, while abnormal forms increased from 87.7 ±7.4 in normal to 90.9 ±6.6 & 91.6 ±8.1 in overweight and obese (P= 0.04. Motility decreased from 14.3 ± 4 .2 in normal to 13.3 ± 3.45 & 11.8 ± 5.4 in overweight and obese (P= 0.007), teratozoospermia index increased from 1.28 ± 0 .18 in normal to 2.38 ± 0.17 and 3.29 ± 0.22 in overweight and obese (P= 0.009), the same findings was observed in sperm deformity index. Conclusion: Obesity may play a negative role in sperm parameters and male subfertility.