Acute leukemia is uncommonly seen with rheumatoid arthritis during or following treatment with low-dose methotrexate, a safe and effective treatment for the arthritic condition. We describe here a 68-year-old woman with rheumatoid arthritis who developed acute erythroleukemia during low-dose methotrexate therapy (total dose 1702.5 mg). This may be the first such case reported in the literature.