A patient with rheumatoid arthritis presented with pancytopenia 3 weeks after initiation of low-dose methotrexate administered orally. She had minimal renal insufficiency and hypoalbuminemia prior to initiation of methotrexate therapy, and had received a nonsteroidal anti-inflammatory drug concurrently. Bone marrow recovery occurred within 3 weeks. Patients receiving low-dose methotrexate therapy for rheumatoid arthritis require early monitoring for bone marrow injury, especially those who have risk factors for possible methotrexate toxicity.