The aim of this study was to determine whether body mass index (BMI) is associated with clinical response to biologics in patients with rheumatoid arthritis (RA). We enrolled 68 patients with RA who were treated with biological disease-modifying antirheumatic drugs (bDMARDs). Biologics included abatacept, tocilizumab, and tumor necrosis factor-α (TNF-α) blockers (etanercept and adalimumab). Baseline BMI (kg/m(2)) was classified as normal (BMI < 23.0), overweight (23.0 ≤ BMI < 25.0), or obese (BMI ≥ 25.0). Improvement of disease activity score 28 (DAS28) and achievement of the European League Against Rheumatism (EULAR) remission and responses between baseline and 24 weeks were our measures of clinical improvement. Mean baseline BMI before treatment with bDMARDs in patients with RA was 22.2 (SD 3.6). DAS28-ESR and DAS28-CRP were significantly reduced from baseline after 24 weeks of treatment with bDMARDs (p < 0.001 of both). ∆DAS28-ESR and ∆DAS28-CRP were not found among patients with normal, overweight, or obese BMI (p = 0.133 and p = 0.255, respectively) nor were EULAR responses or EULAR remission (p = 0.540 and p = 0.957, respectively). Logistic regression analysis showed no relationship of BMI with EULAR clinical responses (p = 0.093 for good response and p = 0.878 for EULAR remission). This study reveals that BMI is not a predictive factor of clinical response to bDMARDs in patients with RA.