For patients with hematologic malignancies, novel therapeutic strategies offer the potential to achieve a complete clinical response and long-term survival. However, declining fertility has become a significant concern, impacting long-term quality of life. Conventional high-dose chemotherapy and radiotherapy are known to reduce fertility or cause sterility. Moreover, limited clinical data are available on the effects of newer therapies, such as targeted treatments and chimeric antigen receptor (CAR)-T cell therapy, on fertility. Additionally, there is no standard method for preserving fertility in these patients. Male patients can opt for sperm cryopreservation, whereas female patients may preserve fertility through embryo, oocyte, or ovarian tissue cryopreservation. However, preserving fertility in prepubescent patients remains particularly challenging. Therefore, hematologists must educate patients about the potential gonadal toxicity of cancer treatments and offer the most appropriate fertility preservation options.