Introduction: In older men, sexual disorders may be the result of a decrease in testosterone and an increase in sex hormone binding globulin (SHBG) serum levels. Although obesity may enhance the decline of testosterone, it is also the cause of metabolic disorders, which are additional risk factors of erectile dysfunction. The purpose of this study was to investigate whether elevated body weight is associated with decreased serum testosterone concentrations and reduced sexual function in young men. Material and methods: Data on general health, medication, depressive symptomatology and sexual life was obtained from 136 men aged 20-49 years. Blood levels of LH, total testosterone (TT), dehydroepiandrosterone sulfate (DHEA-S), oestradiol, SHBG, total cholesterol, LDL-and HDL-cholesterol, and triglycerides were determined. Body mass index (BMI), waist to hip ratio (WHR) and free testosterone index (FTI) were calculated. Results: A significantly reduced occurrence of sexual fantasies, morning erections and erectile function scores was observed in the oldest group compared to the youngest men with normal BMI, although orgasmic function was unchanged. A significant decrease in TT serum levels was observed in obese 30-year-olds compared to men with normal BMI, while in obese 40-year-olds decreased LH and SHBG levels were also found. No differences in the levels of lipids and sexual achievements were found among men with different BMI. However, erectile function and morning erections significantly negatively correlated with age, BMI and WHR, and positively with FTI, but not with other studied hormones and lipids.