This study investigates the relationship of hand use to the deforming hand joint changes of rheumatoid arthritis. Measurements of metacarpophalangeal lateral mobility, loss of metacarpophalangeal hyperextension, thumb metacarpophalangeal range of motion, and lateral pinch strength were statistically compared across dominant and nondominant hands of 51 adult subjects who had definite or classical rheumatoid arthritis. Incidence of boutonniere and swan neck deformities and distal radioulna laxity was also recorded. Results of a multivariate analysis of variance of the difference scores between dominant and nondominant measures were not significant. The authors concluded that the relationship of hand use to joint destruction is not yet clearly defined and further study is needed. Implications for treatment principles of joint protection are presented.