Background/aim: We aimed to compare the results of unilateral and bilateral varicocele surgery. Materials and methods: In two referral hospitals, the data of 180 patients who were treated with unilateral and bilateral microscopic varicocelectomy were retrospectively analyzed. Sperm parameters and spontaneous pregnancy rates were compared in patients who underwent bilateral and unilateral microscopic varicocelectomy. Results: The mean age was 29.6 (17-46) years. While 82 patients underwent unilateral varicocelectomy (Group I), 98 patients underwent bilaterally varicocelectomy (Group II). Forty (48.8%) spontaneous pregnancies occurred in Group I and 59 (60.2%) in Group II. When we analyzed sperm parameters, the rate of increase in the number of sperm in spermiograms was 17% in Group I and 27.5% in Group II. The rate of increase in sperm mobility was 58.5% and 50% in Group I and II, respectively. The improvement rate in sperm morphology was 46.3% in Group I and 56.1% in Group II. There were no significant differences between all these parameters. Conclusion: In light of our results, although pregnancy rates seemed to be higher in patients who underwent bilateral varicocelectomy, these results were not statistically significant. Improvement rates in sperm parameters were similar between the patients who underwent unilateral and bilateral varicocelectomy.