OBJECTIVE To evaluate the toxicity and clinical efficacy of liposomal encapsulated doxorubicin (DOX-SL) in the treatment of HIV-related Kaposi's sarcoma (KS). METHODS DOX-SL 20-40mg/m2 was administered by intravenous infusion over 30-60 minutes every two weeks. Toxicity was assessed in all patients and response assessed in patients who completed two or more cycles of therapy. RESULTS Twenty-five patients with KS were enrolled. Nine had received previous KS chemotherapy but only one prior anthracycline therapy. Eighteen patients had CD4 counts < 50/mm3. Eight had pulmonary and/or visceral KS. A total of 191 cycles were given, median 6, range 1-33. Twenty patients completed two or more cycles and were considered evaluable for efficacy. A defined response occurred in 11 patients, nine achieving a partial response and two a complete response. The median duration of response was 120 days and the median time to disease progression was 187 days. Acute toxicity was minimal, except in one patient who had generalised erythema, hypotension and diaphoresis within ten minutes of starting DOX-SL infusion. Grade 3 or 4 neutropenia occurred in 13.6 and 3.7% of cycles respectively. Neutropenic sepsis secondary to drug therapy was not reported. Alopecia and gastrointestinal symptoms were mild and infrequent. No cardiac toxicity was seen. Nine/25 patients developed HIV-associated illnesses while on study (three Pneumocystis carinii pneumonia, two systemic Cytomegalovirus infection, three cryptosporidiosis, one Mycobacterium avium intracellulare--(MAC) infection). Median survival in the evaluable patients was 219 days. CONCLUSIONS DOX-SL is an effective and well tolerated palliative therapy in AIDS-related KS.