Fifteen men with HIV-associated Kaposi's sarcoma (KS) and poor risk disease according to the TIS staging were enrolled in a phase II trial of oral 13-cis-retinoic acid. The median CD4 cell count was 95 cells/microl (range 7-260) and 6 had prior AIDS-defining opportunistic infections. One patient was withdrawn on account of cutaneous toxicity. Evaluation was by AIDS Clinical Trials Group (ACTG)1 defined assessment. One patient achieved a partial response and remains on treatment in partial remission. Thus the overall response rate is 7% (95% confidence interval 0-23%). A further 5 patients had stable disease (38%: 95% confidence interval 7-64%). The overall low activity, considerable toxicity and limited cosmetic benefit even in responding patients limits the value of this approach in KS. However, this treatment strategy may be more rewarding in early good risk KS.