The design of a prospective phase-II study on the treatment of Kaposi's sarcoma (KS) in patients with HIV infection is described. In this study the toxicity and antineoplastic activity of high-dose alpha-interferon (20 x 10(6) U/m2 s.c. daily) will be investigated in patients with advanced and progressive KS. Patients with progressing KS during IFN treatment or with relapsing KS after IFN will be treated with vinblastine (4 mg/m2 i.v., days 1, 8, and 15) and bleomycin (15 mg i.v., days 1 + 8). The study was only recently activated; results are so far not available.