A number of patients with rheumatoid arthritis attending the Rheumatology Clinic at St Luke's Hospital are currently receiving the drug methotrexate as a second line disease-modifying agent. A survey has been conducted to assess the toxicity profile of methotrexate in 33 of these patients who were followed up for at least 1 year or until they developed side effects necessitating discontinuation of treatment. Adverse effects in this group of patients included haematological ones (6%), asymptomatic elevations of liver enzymes (57%), gastrointestinal (6%) and dermatological side effects (3%). These results have been compared to larger studies performed abroad. Regular monitoring of a complete blood count and liver function tests has helped to detect the more serious side effects of methotrexate at an early stage enabling successful intervention in these patients.