A 45-year-old woman with rheumatoid arthritis(RA) who developed nephrotic syndrome and acute renal failure was reported. She first noticed polyarthritis in June 1990, and was diagnosed as RA. Since her RA was not controlled with nonsteroidal anti-inflammatory drugs (NSAID), she started taking prednisolone 10 mg daily and received 100 mg of D-penicillamine from October 1990 with improvement of the RA. In March 1991, she noticed edema of the face and legs, at which time massive proteinuria and hematuria were first noted. Because of her nephrosis, she was referred to our hospital for further evaluation. Laboratory investigations revealed 24-hour urine proteinuria of 37 g, serum creatinine, 2.7 mg/dl, blood urea nitrogen, 43.5 mg/dl, total protein, 4.1 g/dl, albumin, 1.5 mg/dl, and total cholesterol, 600 mg/dl. The rheumatoid factor and anti-nuclear antibody were positive. Renal biopsy showed focal segmental glomerulosclerosis (FSGS). Her nephrotic syndrome and renal dysfunction recovered after the administration of prednisolone at 60 mg/day. The possible pathogenesis of FSGS in patients with RA was discussed.