Objective: To compare the surgical outcomes of subinguinal and high inguinal approaches for microsurgical varicocelectomy. Methods: A total of 81 patients with left varicocele were randomly assigned to undergo microsurgical left varicocelectomy by the subinguinal (n = 41) or high inguinal (n = 40) approach. These two techniques were compared with regard to the operative parameters, complications and testicular growth. Anatomical parameters, including the numbers and diameters of internal spermatic arteries, veins and lymphatic vessels, were recorded. Results: The microsurgical step was significantly shorter for the high inguinal approach compared with the subinguinal approach (25.5 vs 33.3 min, respectively, P < 0.01). The numbers of preserved arteries and ligated veins were significantly greater and the artery size was significantly smaller for the subinguinal (1.6 arteries, 11.5 veins and 1.1 mm, respectively) compared with the high inguinal approach (1.2 arteries, 7.3 veins and 1.3 mm; P < 0.001, <0.0001 and <0.01, respectively). There was one patient with postoperative hydrocele, and three with persistent scrotal pain after treatment with the subinguinal approach. The postoperative catch-up growth rates at 24 months were 70% and 78% for the subinguinal and high inguinal approaches, respectively. Conclusions: The microsurgical subinguinal and high inguinal approaches seem to yield similar success rates in terms of testicular growth. However, the high inguinal approach is easier to carry out, as it requires fewer divisions of veins and is associated with a larger diameter of the spermatic artery.