Traditionally there is a concern about the possibility of developing testicular tumors as a consequence of undescended testis. This study was conducted to investigate the correlation between testicular tumors and undescended testis.Medical records of all patients with testicular germ cell cancer were seen and examined at the Princess Basma Teaching Hospital, Jordan University of Science and Technology, Irbid, Jordan, between 1990 and 2000 (group 1) for any evidence of undescended testis. All males with undescended testis attending the infertility clinic during the period 1999-2001 (group 2) were re-evaluated for any evidence of testicular tumors. The operative records of all patients who had surgery for undescended testis during the past 30 years (group 3) were reviewed and the patients were contacted to see if any of them developed testicular tumor as expected.Forty-four patients with testicular germinal cell tumors; mean age at diagnosis were 32.6 years (range 20-50) were identified. All patients had unilateral involvement and none of them were found to have tumors in undescended testis. The tumor was in the scrotum in all patients. None of the 117 infertile patients with undescended testis had clinical or ultrasonic evidence of testicular tumors. Two thousand nine hundred and nineteen patients had an operation for undescended testicle in the past 30 years, average of 97.3 operations annually. Median age at surgery for undescended testis was 7.7 years (range 2-29 years). None of the 2071 patients who were traceable developed testicular tumor.We found no evidence to support that patients with undescended testis are at a higher risk than the general population to develop testicular cancer.