We describe the clinical and pathologic features of a case of pediatric multicentric Kaposi's sarcoma (KS) associated with allograft transplantation in a human immunodeficiency virus (HIV)-negative child. A lethal polyadenopathic and visceral KS occurred in a 5-year-old Caribbean boy who had undergone an allogenic renal transplantation for diffuse mesangial sclerosis with end-stage renal failure 4 months previously. The HIV-1 and HIV-2 serologies were negative. Despite its rarity, KS must be considered as a differential diagnosis in posttransplantation polyadenopathic or multisystemic syndromes in children.