A previously healthy woman in her 40s presented with 6 months of bilateral leg edema, insomnia, and myalgias. One month after symptom onset, her creatinine level was 0.80 mg/dL (71 μmol/L) (reference, 0.50-1.19 mg/dL [44-105 μmol/L]) and 24-hour urine protein content was 8.7 g (reference <0.15 g). Kidney biopsy revealed thickening of the glomerular basement membrane with electron-dense deposits, consistent with membranous nephropathy, stage 2. She was treated with 3 days of methylprednisolone (500 mg) and cyclophosphamide (400 mg), followed by prednisolone (1 mg/kg/d) for 8 weeks, subsequently tapered by 10 mg every 4 weeks. Four weeks after initial treatment, proteinuria had decreased to less than 0.5 g/d, but proteinuria increased to 6.72 g/d when the prednisolone dosage was decreased to 20 mg/d.