OBJECTIVES: To evaluate the effect of spermatic vein ligation in patients over 30 years old and with low-grade left varicocele, and thus help to establish whether such patients might benefit from surgery. PATIENTS AND METHODS: A randomized study was conducted on 68 infertile patients (30-38 years old) with evidence of sperm abnormalities and who had low-grade varicocele (grade I according to Hirsch), comparing left spermatic vein ligation with no treatment. The outcome was assessed by standard sperm analysis and eventual paternity. RESULTS: There was no improvement in sperm quality in either of the groups one year after surgery, and no significant difference in paternity. CONCLUSIONS: Left spermatic vein ligation for low-grade varicocele in patients more than 30 years old cannot be recommended.