BACKGROUND. Intracytoplasmic sperm injection (ICSI) allows pregnancies to be established with a single sperm, improving the chances for men with severely impaired sperm quality to cause a pregnancy. Men with leukemia typically are of reproductive age and their fertility is threatened by initially impaired semen quality and cytotoxic chemotherapy. The authors examined the feasibility of sperm cryopreservation in men with leukemia before treatment and whether the type of leukemia is related to prefreeze or postthaw semen quality. METHODS. Records of 25 patients with acute (n = 13) or chronic (n = 12) leukemia who banked their Sperm were reviewed. Semen characteristics were compared with those of normal donors (n = 50) and between the 2 patient groups before and after cryopreservation. Motile sperm count (MSC), motility, curvilinear velocity (VCL), linearity, and amplitude of lateral head movement were compared between patients and healthy donors. No patient had undergone chemotherapy before sperm banking. The nitrogen vapor technique was used for sperm cryopreservation. RESULTS. Patients with leukemia had significantly lower prefreeze and postthaw MSC (P = 0.0001), motility (P < 0.05), and VCL (P < 0.05) compared with healthy donors. The percentage change from prefreeze to postthaw in MSC and motility (P < 0.05) was significantly greater in patients than in healthy donors. The effect of cryopreservation on semen quality was similar in patients with both acute and chronic leukemia. CONCLUSIONS. Patients with leukemia have poor prefreeze and postthaw semen quality compared with healthy donors. In this study the type of leukemia did not appear to affect prefreeze or postthaw semen quality and the postthaw MSC was sufficient for use with ICSI. Sperm cryopreservation should be offered to all men of reproductive age before the initiation of therapy for leukemia.