Abstract Background: Body mass index (BMI) in the population is increasing. At present, numerous studies have concentrated on the effect of overweight on female reproduction. A decrease in semen quality has paralleled this increasing prevalence of obesity in the developed world. The purpose of this report was to summarize the evidence on the association between semen parameters and BMI. Methods: This study is a literature review of articles pertaining male obesity and reproduction. Relevant studies published until January 2015 were identified from a systematic search in Pubmed and EMBASE. Abstracts of relevant articles were examined and the articles that satisfied the inclusion criteria were retrieved. Result: The work is based on 30 primary studies, with a total of 45,730 men and included both men attending fertility clinics and men from the general population. An overview of the association between BMI and semen parameters is presented. Conclusion: This literature review has shown a preponderance of studies, that have found a correlation between BMI and male fertility. 21 primary studies out of 30 with a total of 36,229 participants did find a significant negative correlation between BMI and semen quality, as opposed to 9 primary studies with a total of 9501 participants who did not find any significant correlation. The results are conflicting, but the majority of the studies indicate that obesity in men is associated with reduced semen parameters. Since the included studies have different research design, it is problematic to draw a clear conclusion.