The aim of this study is to identify the factors associated with nutrition in Japanese patients with rheumatoid arthritis (RA). Overall, 409 patients with RA who underwent the Mini Nutritional Assessment (MNA), bone mineral density determination, and body composition assessment by bioelectrical impedance analysis were enrolled. The analysis of factors associated with malnutrition was performed by comparing groups categorized by MNA score ($24, 17-23.5, and ,17). Moreover, correlation analysis for MNA score and variables was performed. The factors associated with malnutrition were the Health Assessment Questionnaire Disability Index (HAQ-DI) (p50.005; odds ratio, 1.98), fat-free mass index (FFMI) (p50.002; odds ratio, 0.59), and fat mass index (FMI) (p50.022; odds ratio, 0.75). Statistical correlations of the MNA score with the following variables were observed: HAQ-DI (correlation coefficient [R], 20.261; p,0.001), FFMI (R, 0.371; p,0.001), and FMI (R, 0.272; p,0.001). This study identified nutrition-associated factors in Japanese patients with RA. The nutrition-associated factors were HAQ-DI, FFMI, and FMI. Therefore, physicians should evaluate nutrition of patients with RA.