We attempted to determine the testicular volume changes in patients with unilateral varicocele, before and after varicocelectomy. Testicular volume differences were correlated for each group of varicocele grade. 123 men with a unilateral left varicocele were presented for surgery: 36 had grade I, 49 had grade II, and 38 had grade III varicoceles. A Prader orchidometer was used for testicular volume determination before and after varicocelectomy in each patient. Both left and right testicular volumes were compared. After the repair of grade I varicoceles, an improvement in testicular volumes was noticed, but the difference was not statistically significant (p > 0.05). Both right and left testicular volumes increased significantly after operation in patients with grades II and III varicoceles (p < 0.001). Right testicular volume improved more than left in most of the patients. Men with large varicocele had significantly decreased testicular volumes than men with small varicocele before operation. So testicular growth arrest was more significant in patients with large varicocele and postoperative results indicated a more dramatic improvement.