Doxorubicin is an anthracycline antibiotic which has a wide range of clinical activities. The mechanism of cytotoxicity and the exact intracellular target remains controversial. The bulk of intracellular drug is intranuclear much of which is intercalated in the DNA. Although DNA intercalation has been felt to be the principle cytotoxic mechanism, more recent evidence suggests inhibition of topoisomerase-II may play a more important role. Additionally, other cytotoxic actions including helicase inhibition have recently been noted. Pegylated liposomal doxorubicin (Doxil) is a polyethylene glycol pegylated liposomal encapsulation of doxorubicin. This results in an alteration of the pharmacokinetics in comparison to the parent compound. Specifically there is a prolonged circulation time, reduced clearance, a smaller volume of distribution, and limited uptake by the reticuloendothelial system. In animals using ovarian xenografts in nude mice, pegylated liposomal doxorubicin has resulted in a greater tumor to normal tissue drug uptake and an improved therapeutic index. Following phase I studies, Doxil has recently been studied in a phase II study of heavily pre-treated ovarian carcinoma patients with a response rate of 25.7%. This level of activity meets or exceeds other second-line agents currently available. In the recent phase II study, a dose of 50 mg/m2 every 3 weeks was utilized.