The purposes of this study were to explore the relationships between physical function, knowledge of disease, social support, and self-care behavior in patients with rheumatoid arthritis and to examine the predictive variables of self-care behavior. A cross-sectional design was developed and implemented in which 115 subjects with rheumatoid arthritis were recruited from two hospitals located in southern Taiwan. Findings demonstrated a significantly positive correlation between self-care behavior and age, physical function and social support. Age and social support represented the effective predictors of self-care behavior, explaining 13.4% of total self-care behavior variance. Study results suggest that healthcare providers should better understand the predictive factors of self-care behavior, design effective interventions and provide therapeutic information in order to facilitate better self-care behavior in patients with rheumatoid arthritis.