We assessed the effect of smoking and/or obesity on semen parameters and testosterone/oestradiol (T/E) ratio among sub‐fertile men treated with sub‐inguinal varicocelectomy. In this prospective, controlled, clinical study, 80 sub‐fertile men with clinical varicocele who were subjected to sub‐inguinal varicocelectomy were assigned into four equal groups (n = 20/each), group A: obese and smokers, group B: obese and nonsmokers, group C: smokers and nonobese and group D: nonsmokers and nonobese. Semen parameters, serum testosterone, oestradiol, follicle‐stimulating hormone, luteinising hormone, prolactin and calculation of T/E ratio were assessed at baseline and 6 months post‐varicocelectomy. The mean age ± SD of the study population was 26.1 ± 4.55. No statistical difference was detected among the study groups regarding age, residence, education, marital status and occupation (p > 0.05 for each). Post‐operatively, significant improvements in semen parameters were detected in all groups. There was a significant difference between groups A and B versus C and D (obese versus nonobese groups) and between groups A and C versus B and D (smokers versus nonsmokers; p < 0.05 for each) regarding semen parameters, testosterone level and T/E ratio. Smoking and/or obesity negatively affect(s) the favourable outcome of varicocelectomy, specifically improvement of semen parameters and hormonal pattern in sub‐fertile men with varicocele.