Purpose: Evaluate the effect of undescended testes on semen in adult cryptorchid patients. Patients and method: This study was carried out in adult cryptorchid patients operated at Urology department of Viet Duc hospital and in whom semen analysis was performed pre-operatively during the period from January 2011 to July 2013. All results of semen analysis were collected and analyzed. Results: Semen volume of patients with bilateral undescended test:es was less than that of patients with unilateral undescended testis (p0.05). Semen volume of patients was not affected by testicular location (p0.05). All 31 patients with bilateral undescended testes were azoospermia, yet the rate of azoospermia in patients with unilateral undescended testis was 22.6 percent (12 patients)
the difference was significant (p0.05). The sperm concentration in patients with unilateral undescended testis were not affected by testicular location (p0.05). Some other characters of sperm in patients with unilateral undescended testis such as survival rate, rate of. normal morphology, rate of mobilization were not affected by testicular location (p0.05). Conclusion: Semen is affected by cryptorchid condition, especially bilateral cryptorchidism. Thus, patient's reproductive possibility is also affected. In patients with unilateral cryptorchidism, semen volume, sperm concentration, sperm quality are affected but testicular location doesn't cause a significant difference.