Objective To explore the imaging characteristics of seminomas and nonseminomatous germ cell tumors (NSGCT) and its pathological foundation. Methods CT and MR imaging manifestations in 25 cases of testicular germ cell tumors proved by pathological examinations were analyzed retrospectively. All tumors were divided into seminomas group (12 cases) and NSGCT group (13 cases). In the seminomas group, 5 cases were examined by CT and 4 of those also had contrast enhanced CT. Seven cases had MRI and 4 of those had dynamic enhanced MRI. In the NSGCT group, 5 were examined by plain CT in which two were by contrast enhanced CT, eight were by MRI in which 4 were by dynamic enhanced MRI. CT or MRI characteristics (morphology, density or intensity, enhancement) in both groups were analyzed by Fisher test. Results Histological examination revealed 25 intratesticular lesions. In 12 seminomas, 10 showed a nodular/lobulated shape, 5 showed a mixed density or intensity. In 13 NSGCT, only one lesion showed a lobular shape, 11 showed a mixed density or intensity. Seven seminomas showed a low signal on T2WI on MRI while only two NSGCT showed this sign. In four lesions underwent dynamic MRI scanning, 3 showed fibrous septum enhancement while no lesions in NSGCT showed this sign. The occurrence rate of the above imaging characteristics in both group was significantly different (P<0.05). Conclusion Seminomas and NSGCT may have their own CT and MRI characteristics, which may be of great value for differential diagnosis .