The aim of this study was to investigate the effects of gonadotropin releasing hormone analog (GnRHa) therapy on normalized testicular atrophy index (TAIn) using gonadorelin before and after orchiopexy. 62 infants with 87 undescended testes (UDT) were prospectively assigned to two homogeneous groups according to age, position of UDT and TAIn. The patients were randomized to receive either orchiopexy alone or orchiopexy combined with GnRHa as nasal spray at 1.2 mg daily for 4 weeks before surgery and 4 weeks after surgery. Surgical approaches were relative to the position of the UDT: Shoemakers technique in proximal-UDT and Bianchi technique in distal-UDT. All the patients were evaluated clinically and sonographically 1 month before surgery, at the time of surgery, 1 month, 6 months and 5 years after surgery. Ultrasound data in our study have shown a statistically significant decrease of TAIn in children given additional HT only after 5 years of follow-up, in unilateral cases and in the entirety of treated patients; in bilateral cases this difference was not statistically significant. Patients with a TAIn >20 % treated with preoperative and post-operative GnRHa therapy have a significant increase in testicular volume after 5 years of follow-up, as shown by the relative reduction of TAIn values.