Mitoxantrone is an antitumor agent that was synthesized to try to develop a doxorubicinlike drug with a better therapeutic index. It has clinical activity for acute leukemias, breast carcinoma, non-Hodgkin's lymphoma, and ovarian cancers. There is some lack of cross-resistance to the anthracyclines. Its spectrum of toxicity is advantageous in that it causes less alopecia and can be administered for a slightly longer time than doxorubicin. For selected patients, mitoxantrone can be useful as a substitute for doxorubicin, but doxorubicin will remain the more widely used drug.