Trabectedin (ET-743, Yondelis®) is a novel marine antineoplastic alkaloid with a unique mechanism of action. The active substance trabectedin, a tetrahydroisoquinoline alkaloid, is a natural product originally isolated from the Caribbean sea squirt, Ecteinascidia turbinata and is currently manufactured by total synthesis. Trabectedin is licensed by the Spanish pharmaceutical drug company, PharmaMar and co-developed by Johnson & Johnson Pharmaceutical Research and Development, L.L.C., pursuant to a licensing agreement with PharmaMar. Trabectedin is the first anticancer marine-derived drug to be approved by the European Union. In 2007, trabectedin obtained marketing authorization from the European Commission and in many other countries worldwide for the treatment of patients with advanced soft tissue sarcoma (STS) after failure of anthracyclines and ifosfamide, or for those patients who are unsuitable to receive these agents. Based on the recently reported results of a large phase III study (OVA-301) comparing pegylated liposomal doxorubicin (PLD) alone with a combination of PLD and trabectedin in patients with recurrent ovarian cancer, in 2009 the European Commission granted marketing authorization for trabectedin combined with PLD for the treatment of patients with relapsed platinum-sensitive ovarian cancer. The results from OVA-301 showed that the combination of trabectedin and PLD improves progression-free survival and overall response rate over PLD alone with acceptable tolerance in the second-line treatment of recurrent ovarian cancer. In addition, an enhanced activity of trabectedin combined with PLD was observed in platinum sensitive patients, especially in those with a platinum-free interval ranging from 6 to 12 months. Overall, trabectedin-induced toxicities are mainly hematological and hepatic, with grade 3/4 neutropenia and thrombocytopenia observed in approximately 50% and 13% of patients, respectively, and grade 3/4 elevation of liver aminotransferases observed in 40-50% of patients treated with trabectedin. Current efforts are focused on the evaluation of the role of trabectedin in prolonging the platinum-free interval and the identification of predictive factors for patients treated with trabectedin as well as in the development of new trabectedin-based combinations.