A study of fertility was conducted in postpubertal male patients who had been treated for acute lymphoblastic leukemia (ALL) during childhood or adolescence between 1970 and 1980. Thirteen men (age 18 to 35 years) participated on a volunteer basis. Their age at diagnosis was between 2 and 15 years. Therapy followed the protocol ''Memphis VII (Pinkel)." Interview, physical examination, andrological studies (ejaculate), and hormone status (luteinizing hormone, follicle-stimulating hormone, and testosterone) were performed at least 5 years after completion of therapy. No normozoospermia was achieved; 10 patients were identified with asthenozoospermia and 3 patients with azoospermia. With respect to these data, patients treated for ALL between 1970 and 1980 have more significantly impaired spermatogenesis than expected.