We describe a case of simultaneous severe lupus enteritis and lupus cystitis in a 38-year-old female with a 21-year history of systemic lupus erythematosus (SLE). The patient presented with acute abdominal pain, decreased urinary output, associated low-grade fever, nausea, and diarrhea. She had serologic evidence of an SLE flare with acute renal insufficiency. Computed tomography examination revealed dramatic edema of the large- and small-bowel walls with no evidence of bowel loop dilatation or pneumatosis intestinalis, marked diffuse thickening of the urinary bladder wall, and bilateral hydronephrosis and hydroureter. Lupus enteritis and lupus cystitis were diagnosed and treatment with intravenous corticosteroids led to prompt resolution of the abdominal pain and normalization of renal function. Because infarction of tissue and bowel rupture are potentially fatal complications, it is essential to consider lupus enteritis in SLE patients who present with abdominal pain. This case demonstrates that once lupus enteritis is suspected, coexistent lupus cystitis must also be considered.