Adherence to medication in patients with rheumatoid arthritis is low, varying from 30 to 80%. Improving adherence to therapy could therefore dramatically improve the efficacy of drug therapy. Although indicators for suboptimal adherence can be useful to identify nonadherent patients, and could function as targets for adherence-improving interventions, no indicators are yet found to be consistently and strongly related to nonadherence. Despite this, nonadherence behavior could conceptually be categorized into two subtypes: unintentional (due to forgetfulness, regimen complexity or physical problems) and intentional (based on the patient's decision to take no/less medication). In case of intentional nonadherence, patients seem to make a benefit-risk analysis weighing the perceived risks of the treatment against the perceived benefits. This weighing process may be influenced by the patient's beliefs about medication, the patient's self-efficacy and the patient's knowledge of the disease. This implicates that besides tackling practical barriers, clinicians should be sensitive to patient's personal beliefs that may impact medication adherence.