Quinine-induced immune thrombocytopenia with hemolytic uremic syndrome (HUS) is a recently defined clinical entity. In this paper we have attempted to characterize the natural history and laboratory abnormalities typical of quinine-induced immune thrombocytopenia associated with hemolytic uremic syndrome in nine patients experiencing ten episodes of the disease. In addition, review of other reported cases of probable quinine-induced HUS is presented. The disease was characterized by the onset of chills, diapheresis, nausea and vomiting, abdominal pain, decreased urine output, and petechiae following quinine exposure. All patients experience significant anemia, severe thrombocytopenia, increased lactate dehydrogenase, elevated serum creatinine, and oliguria. Quinine-dependent platelet-reactive antibodies were identified in eight of nine using flow cytometry. Unexpectedly, drug-dependent antibodies reactive with red cells and granulocytes were identified in four and eight patients, respectively. All patients were treated with plasma exchange (range 1-12 procedures), and seven required hemodialysis. All survive without residual abnormality. Our experience with nine patients with quinine-induced HUS and the nine additional cases reported by others and reviewed in this paper establishes this condition as a distinct clinical entity. Adult patients presenting with HUS should routinely be asked about exposure to quinine in the form of medication or beverages. The mechanism by which quinine-dependent antibodies produce renal failure is uncertain, but preliminary studies (described elsewhere) suggest that drug-induced antibodies reactive with endothelial cells and possibly margination of granulocytes in renal glomeruli may be responsible for this complication. The prognosis in quinine-induced HUS is better than in other forms of adult HUS.