We report the case of a patient with acute renal failure and nephrotic syndrome during the second trimester of an otherwise uncomplicated pregnancy. Despite pregnancy, percutaneous renal biopsy was performed to evaluate the etiology, showing Type I membranoproliferative glomerulonephritis. Two therapeutic options were considered: pregnancy termination, suggested by the gynecologists, and our proposal of starting steroid therapy, in order to reduce proteinuria and improve renal function. The patient refused pregnancy termination. She received i.v. methylprednisolone boluses, followed by maintenance oral prednisone and aspirin, with prompt acute renal failure resolution and reduced proteinuria. At Week 34 + 5 days of gestation, cesarean section was performed, without intra- and postoperative complications both for mother and newborn. Clinical maternal and fetal outcomes were excellent. One-year follow-up showed normal renal function and absence of proteinuria. Lacking guidelines concerning treatment of acute renal failure due to primary nephropathy in pregnancy, we consider this case of interest for our decision-making process and for the favorable outcome.