OBJECTIVE To investigate which clinical variables contribute to the function of the hand in activities of daily living (ADL) in patients with rheumatoid arthritis (RA). METHODS In 50 patients with RA hand function in ADL was assessed by (1) the dexterity items of the Arthritis Impact Measurement Scales (AIMS), (2) direct observation of the same items by an occupational therapist, and (3) the Jebsen hand function test. A combined hand function factor was constructed by principal component analysis of the 3 hand function measures. Further assessments included measurements of muscle strength, deformity and destruction, range of motion, and local arthritis activity. After bivariate analyses, variables that correlated significantly with the measures of hand function were entered into stepwise multiple regression analyses. RESULTS The variables having a significant correlation with most of the hand function measures were: pinch and grip strength, patient's assessment of pain and stiffness of the hands, flexion of the thumb and fingers, range of motion of the wrist, alignment of the metacarpophalangeal (MCP) joints, swan neck and Z deformities, and the Larsen erosion score. 78% of the variance of the combined hand function factor could be explained by pinch strength, stiffness of the hands, and the presence of Z deformity and ulnar deviation. CONCLUSIONS Pinch and grip strength should be carefully considered in setting goals for conservative or surgical treatment of the rheumatoid hand. In addition, reported stiffness of the hands, malalignment of the MCP joints, and flexion and deformity of the thumb were the most consistent indicators of impaired hand function.