Combination therapy with methotrexate may be the newest standard to which future therapies for rheumatoid arthritis are compared. Many questions remain to be answered regarding the appropriateness of such combination therapies for specific patients and clinical situations, and the optimal therapeutic combinations. Other unanswered questions regarding combination therapy include the need for appropriate monitoring, long-term safety and cost-benefit implications. Future research is needed to clarify the role of biological response modifiers (e.g. anti-tumour necrosis factor therapies) and matrix metalloproteinase inhibitors, both as components of and alternatives to methotrexate combination regimens.