Abstract Introduction: A total of 80–90% of all testicular masses are malignant germ cell tumors. Benign testicular lesions are recognized in approximately 10–20% enabling a testis-preserving surgery on the findings of frozen section examination (FSE). However, there are only sparse information with regard to the reliability of FSE in testicular tumors of uncertain dignity. Therefore, we retrospectively reviewed our experience concerning the reliability of FSE in primary testicular tumors by comparing each FSE result to the final diagnosis. Patients and Methods: From 1974 to 2000, 354 patients were operated on a testicular tumor. During inguinal exploration and after clamping of the spermatic cord and appropriate dressing, a representative biopsy of the tumor was taken and sent for FSE. In case of malignancy radical orchiectomy was performed, in case of benign findings or in case of a germ cell tumor in a solitary testicle, the tumor was enucleated. Slides of FSE and the permanent sections were reviewed and compared with regard to the histological diagnosis and presence/absence of malignancy. Results: Based on FSE, 317 tumors (89.5%) were found to be malignant ((100 seminomas (38.5%), 217 nonseminomas (61.5%)) and 37 tumors (10.5%) were benign (17 epidermoid cysts, 14 Leydig cell tumors, two cystadenomas, two simple cysts, two hemangiomas). Comparing FSE and definitive diagnosis, FSE correctly identified all malignant and benign lesions. There was a failure rate of 10 and 8% to differentiate seminomatous from nonseminomatous tumors and vice versa based on FSE, which, however, was irrelevant for the surgical management. Complications of the enucleations ( n=37) were: testicular atrophy in three cases, testicular hematoma in three cases, orchitis/epididymitis in one case. Not a single case disclosed a local relapse after a mean follow-up of 105 (12–240) months. Conclusions: Intraoperative FSE correctly identified all malignant and benign testicular masses including radical orchiectomy or organ-preserving surgery. Surgical management of testicular tumors based on FSE results is clinically practicable.