A child with acute lymphoblastic leukemia (ALL) whose predominant leukemic clone demonstrated double minute chromosomes (dmin) is presented. The patient had no history of mutagen or carcinogen exposure and responded well to combination chemotherapy. Although dmin have been described in acute myelogenous leukemia and various solid tumors in adults, their presence in childhood neoplasms is less frequent and limited primarily to neurogenic tumors. This is the first documentation of dmin in childhood ALL, suggesting that there may be an unrecognized subgroup of ALL patients with gene amplification.