OBJECTIVE This study aimed to evaluate the electromyographic activity of the masseter and temporalis muscles of women with rheumatoid arthritis. METHODS The sample comprised 28 women divided into two groups: 14 with rheumatoid arthritis [mean age: 52.2 ± standard deviation (SD): 3 years] and 14 without rheumatoid arthritis (mean age: 49.4 ± SD: 2.4 years). The women were paired by age and body mass index. The electromyographic activity of the masseter and temporalis muscles was analyzed in mandibular tasks: rest, right and left laterality, protrusion, maximal voluntary contraction with and without Parafilm M®, habitual and non-habitual chewing. The MANOVA (multivariate analysis of variance) was used to compare the means of the two independent groups, considering as independent variable side and diagnosis of rheumatoid arthritis, and age as the covariate. The Bonferroni correction was used for the post hoc comparisons (p <0.05). RESULTS Rheumatoid arthritis group presented an increase in the normalized electromyographic activity of the masticatory muscles and lower mean values for the habitual and non-habitual chewing. CONCLUSIONS Women with rheumatoid arthritis showed functional alterations in the stomatognathic system, demonstrated through muscular hyperactivity and reduction of masticatory efficiency. HIPPOKRATIA 2018, 22(1): 3-9.