Ecteinascidin-743 (ET-743) is a marine-derived antineo-plastic agent undergoing clinical trials to evaluate its use in the treatment of a variety of solid tumors. After the completion of the phase I studies, the agent subsequently was investigated in phase II trials for efficacy in a variety of tumor types. Ongoing phase I evaluation continues with other antineoplastic agents. Side effects of ET-743 include myelosuppression, hepatotoxicity, and nausea and vomiting. Liver function test monitoring is crucial and useful in predicting other serious toxicities. Nursing care issues and patient education are discussed in this article.