Twelve patients with rheumatoid arthritis treated for at least 12 months with methotrexate and 11 matched rheumatoid arthritis controls underwent a standard d-xylose absorption test. No patients had any pre-existing clinical of biochemical evidence of malabsorption. No significant difference was observed in the 1 hour plasma d-xylose estimation between methotrexate treated patients and controls. The 2 to 5 hour urinary excretion ratio, however, was significantly lower in the methotrexate-treated group compared with controls indicating a minor degree of malabsorption. Six of the methotrexate treated patients and 5 of the controls underwent endoscopic duodenal biopsy but neither group demonstrated any significant histological changes. In conclusion, methotrexate therapy in patients with rheumatoid arthritis produces mild intestinal malabsorption.