['To assess the relationship between the body mass index (BMI) and the efficacy of tocilizumab (TCZ) in patients with rheumatoid arthritis (RA).', 'We conducted a retrospective study in 222 patients with RA followed by 5 centers. The European League Against Rheumatism response was evaluated at 6 months. Univariate and multivariate logistic regressions were performed.', 'No significant association between the BMI and the response to TCZ at 6 months was found after adjustment for potential confounding factors (adjusted OR 0.45, 95% CI 0.16-1.24, p = 0.13 and OR 1.19, 95% CI 0.31-4.48, p = 0.78 for BMI 25-30 kg/m(2) and BMI > 30 kg/m(2), respectively, compared to BMI < 25 kg/m(2)).'] Is response to tocilizumab in rheumatoid arthritis influenced by the body mass index of the patient?