It is standard practice to use multiple outcome measures in rheumatoid arthritis (RA) clinical trials. Because of this, multiple testing is usually done, and there is confusion in the interpretation of the results. It is not clear which measures are the most sensitive to detecting improvement and which provide independent information. To address these questions, we conducted an analysis of pooled raw data from 3 placebo-controlled RA trials: one of methotrexate, another of oral and injectable gold, and the third of low-dose and high-dose D-penicillamine. The results show that the joint tenderness count, erythrocyte sedimentation rate, grip strength, and physician assessment of disease activity perform best in RA clinical trials and cover the domain of change measured by traditional outcome measures. Other clinical measures may provide little additional useful information for a standard therapeutic trial of up to 6 months duration, and some measures, such as the proximal interphalangeal joint circumference, hemoglobin level, and 50-foot walking time, can be eliminated from such trials.