We present the case of a 20-year-old man with acute lymphoblastic leukemia who received chemotherapy with vincristine, adriamycin, cyclophosphamide, methotrexate, teniposide (VM-26), and bleomicin, followed by an autologous bone marrow transplantation after total body irradiation (TBI)-cyclophosphamide-based conditioning regimen. At 14 years, despite the severe oligoasthenospermia, he fathered a healthy child by assisted reproductive technique (ART) consisting in controlled ovarian hyperstimulation of the patient's wife, transvaginal ovum pick up and microinjection of the ovum with a previously isolated sperm cell from the patient (intracytoplasmatic sperm injection, ICSI). As far as we know, that is the first documented case of successful paternity using microassisted fertilization with ICSI technique in a patient submitted to TBI-based bone marrow transplantation.