Diffuse petechiae suddenly arose on the back and abdomen of a 79-year-old woman. Within several days, the asymptomatic lesions covered her arms and face as well. Dr Robert P. Blereau of Morgan City, La, reports that chronic lymphocytic leukemia had been diagnosed in the patient 1 year earlier. White blood cell count was 17,800/μL, with 62% lymphocytes and 27% neutrophils; platelet count was 120,000/μL; prothrombin time and partial thromboplastin time were within normal limits. A biopsy of the affected skin revealed nonspecific superficial perivascular inflammation. Vasculitis associated with chronic lymphocytic leukemia was diagnosed. Hypersensitivity vasculitis also occurs in patients with other malignancies, connective tissue disease, essential mixed cryoglobulinemia, and serum sickness. The condition may be associated with Schönlein-Henoch purpura, chronic urticaria, and a urticarial prodrome of acute hepatitis B virus infection. This patient’s petechiae cleared spontaneously from all areas within 2 weeks of onset. A short course of prednisone(Drug information on prednisone) or colchicine(Drug information on colchicine) can be tried if the vasculitis chronically recurs.