The case of an infertile couple in which a testicular seminoma and azoospermia were discovered in the husband during infertility treatment is described. A small piece of testicular tissue, obtained by biopsy from the healthy testis [testicular sperm extraction (TESE)], was deep-frozen before oncology therapy was initiated. The patient's lymphocyte karyotype was normal and no Y microdeletions were found. After conclusion of oncology treatment, the tissue was thawed and successfully used in the intracytoplasmic sperm injection (ICSI) procedure. A healthy girl was born. Testicular tumours are known to impair fertility in the majority of patients, and fertility deteriorates further after cytotoxic and surgical oncology treatment. Until recently in Slovenia, for young oncology patients cryopreservation was applied only to high quality ejaculate fulfilling the criteria for intrauterine insemination or in-vitro fertilization after thawing. Failing that, the only remaining options were fertilization by donor spermatozoa or child adoption. New assisted reproductive technologies, of which the ICSI procedure is the most successful, are suitable for the treatment of only the most severe cases of male infertility. It is reasonable to cryopreserve even poor quality ejaculate prior to the oncology therapy, as well as testicular tissue in cases of azoospermia.