Purpose: Henoch-Schonlein purpura (HSP) is a systemic vasculitis that affects small caliber vessels. Patients present with arthralgias, purpuric rash on the lower extremities, and renal involvement. Gastrointestinal symptoms (abdominal pain, nausea, vomiting, diarrhea, bleeding) are more common in children than adults and usually follow skin manifestations. We present a case of HSP in an adult with gastrointestinal involvement documented endoscopically preceding the onset of skin lesions creating a diagnostic dilemma. A 25 year old healthy woman presented with five days of abdominal pain, nausea, vomiting, diarrhea and haematochezia with a prior upper respiratory tract infection. She denied fever, rash or antibiotic use. Family history was significant for Crohn's disease. Examination showed diffuse abdominal tenderness. Abnormal laboratory data were: WBC 34 k/cumm, ESR 51 mm/hr, CRP 2.4 mg/dl. The following laboratory data were negative or within normal limits: hb, hct, platelets, BUN, creatinine, urinalysis, serum IgA, IBD serology, ttgIgA, stool leucocytes and cultures. Immuno-serological workup was negative. CAT scan of the abdomen showed multiple thickened small bowel loops and edema of stomach and terminal ileum raising possibility of Crohn's disease. Small bowel follow through showed dilated and ulcerated loop of jejunum. Esophagogastroduodenoscopy and colonoscopy were significant for gastritis, erosions and edema of duodenum, sigmoid colon and rectum. Biopsies revealed acute inflammatory changes consistent with immune-mediated vasculitis. Patient subsequently developed arthralgias and diffuse non blanching petechial rash on the lower extremities. Mesenteric angiogram was normal. Skin biopsy showed leucocytoclastic vasculitis. Immunoflourescence stain showed vascular deposits of fibrin and granular IgA. She was diagnosed with HSP and treated with corticosteroids with remarkable improvement. This case illustrates the potential for diagnostic uncertainty when HSP in adults presents with gastrointestinal symptoms preceding skin manifestations.[figure1]Figure