This retrospective study aimed to determine the time for improvement in semen parameters after varicocelectomy. A total of 175 patients over 18 years of age, who underwent microscopic inguinal varicocelectomy in a tertiary centre between 2005 and 2016 and had post-operative follow-up data of at least 12 months, were included in the study. Serial semen analyses in the pre-operative period and at the post-operative third, sixth, ninth and 12th months were retrospectively documented. With respect to their pre-operative total motile sperm counts, the patients were classified into three subgroups as <5 million, 5-9 million and >9 million. In the overall cohort and the group with a total motile sperm count of >9 million, the semen parameters continued to improve up to the post-operative 12th month. No further significant improvement was observed after the post-operative third and sixth months for the patients with pre-operative total motile sperm counts of <5 million and 5-9 million respectively. For the candidates of varicocelectomy, the decision of treatment strategies, such as assisted reproductive technologies and waiting for spontaneous pregnancy can be based on the prediction of the time for improvement in semen parameters.