PURPOSE OF REVIEW: Knowledge of the pathophysiology of Kaposi sarcoma continues to expand and influence our therapeutic approaches. This review summarizes developments within the last 18 to 24 months. RECENT FINDINGS: Pieces of the puzzle as they relate to viral factors-both human herpes virus 8 (HHV-8) and human immunodeficiency virus (HIV)-endothelial cells, host immune factors, and cytokines are described. Recent observations relating to highly active antiretroviral therapy (HAART) and agents under investigation that exploit the developments in pathophysiology are reviewed. SUMMARY: Advances in Kaposi sarcoma pathophysiology are leading to new therapeutic approaches. These will undoubtedly have an impact on other viral and malignant processes as well.