Private hospitals in Japan appear to play an important role in the fertility preservation in cancer patients. However, only a few university-related institutions have published their data about sperm banking. Here we report our experience in a private hospital. The database of 5 years of experience with sperm cryopreservation for male cancer patients was reviewed. We assessed the type of cancer, timing of collection, sperm quality, and utilization for reproductive purposes. There were a total of 88 oncology patients who underwent sperm banking at our institution during the study period. Types of cancer were various, with testicular cancer and hematological malignancies comprising the largest groups. Nearly 90% of the testicular cancer patients had their sperm preserved prior to the therapy, while only 53% of those with hematological disease did so. Evaluation of semen parameters for these groups revealed that oligozoospermia in testicular cancer patients, even prior to initiation of cancer therapy, was common. Five patients utilized their specimens for reproductive purposes. Of these, 3 patients successfully fathered a child. Our results suggest that sperm cryopreservation before initiation of cancer therapy in male oncology patients is under-utilized. Additionally, there is minimal use of cryopreserved specimens for reproductive purposes. This under-utilization is supposed to be due to physicians', especially hematologists', insufficient awareness toward chemotherapy-related infertility and the paucity of reports regarding reproductive outcome after freezing. More data should be compiled to help both physicians and patients who are considering sperm cryopreservation.