The immune response has largely been implicated in the pathogenesis of inflammatory bowel disease (ulcerative colitis and Crohn’s disease) and immunoglobulin A nephropathy. We present a 26-year-old woman with a long past history of asymptomatic macroscopic hematuria who later developed several episodes of bloody stools and abdominal pain. A colonic biopsy disclosed ulcerative colitis and a renal biopsy was consistent with immunoglobulin A nephropathy. Immunoglobulin A nephropathy is the most common glomerulonephritis, being end-stage renal disease a rare but the most serious complication. It can be primary or secondary, but the association between both entities is unusually observed. We discuss the possible immunologic mechanisms involved and believe the initial immunologic derangement originates in the bone marrow. We suggest both conditions must be considered when either a patient with ulcerative colitis and micro- or macrohematuria or with renal involvement and a past history of diarrhea or abdominal pain presents.