A 35-year-old man developed leg edema, marked hypoalbuminemia, and proteinuria. Subsequent renal biopsy revealed a diffuse membranoproliferative glomerulonephritis and, on electron microscopy, typical electron-dense deposits characteristic of an immune complex pathogenesis. Although protein wasting might have readily been explained on the basis of his nephrotic syndrome, the concomitant symptom of diarrhea led to the diagnosis of celiac sprue, another disorder with a possible immune-mediated pathogenesis. While reports of immune complex glomerulonephritis in celiac sprue are rarely recorded, the potential significance of gastrointestinal symptoms in patients with the nephrotic syndrome may have important nutritional implications, especially if underlying occult celiac sprue is recognized.