Cis-diamminedichloroplatinum (II) (DDP) leads the series of platinum coordination complexes, a new class of cytotoxic agents. The antitumor and toxic effects of this drug are discussed. It has displayed encouraging results in testicular tumors. The drug's therapeutic effectiveness has also been recognized in a variety of other solid tumors, particularly ovarian, bladder, and head and neck malignancies. Gastrointestinal, renal, audiologic, and relatively minor hematologic toxicities may be encountered, but promising methods have been developed to increase the therapeutic index of DDP.