Rapidly progressive Kaposi sarcoma (KS) lesions with lymphadenopathy and tissue swelling occurred in a patient during antiretroviral treatment, despite an increased CD4(+) lymphocyte count and decreased HIV-1 level and KS-associated herpesvirus replication, suggesting immune reconstitution inflammatory syndrome. Inflammation resolved coincident with decreases in the CD4(+) lymphocyte count during paclitaxel treatment, whereas KS cleared only after prolonged antiretroviral therapy and chemotherapy.