The objective of this study was to assess the influence of age on the efficacy and toxicity of methotrexate in rheumatoid arthritis. Four hundred and sixty-nine patients were separated according to the age of onset of methotrexate treatment: before 65 yr (group 1, n = 416) and after 65 yr (group 2, n = 53). No difference was found in the evolution of clinical and biological parameters between the two groups. The number of patients in remission at the end of the study was equal. The frequency and type of side-effects were similar. No significant difference was found in the frequency and reasons for methotrexate withdrawal. We noted a trend towards lower therapeutic maintenance of methotrexate when prescribed after the age of 65 yr (P = 0.07, actuarial method). In conclusion, the age at initiation of methotrexate treatment probably did not influence its efficacy and toxicity in rheumatoid arthritis.