It is generally unknown how the attitudes and beliefs of health care professionals (HCPs) might affect the attitudes, beliefs, and medication-taking behavior of patients with rheumatoid arthritis (RA). This study aims 1) to examine the attitudes, health-related associations (both implicit and explicit), and beliefs of HCPs about conventional disease-modifying antirheumatic drugs, and 2) to assess whether these attitudes, health-related associations, and beliefs of HCPs are associated with those of their patients, with their patients' medication-taking behavior, and disease activity. HCPs were recruited from 2 centers that specialized in rheumatology across The Netherlands, and patient recruitment followed. In this observational study, implicit outcomes were measured with single-category implicit association tests, whereas explicit outcomes were measured with a bipolar evaluative adjective scale and the Beliefs About Medicines Questionnaire-Specific. Spearman's rank correlations were used to describe correlations between implicit and explicit measures of the attitudes of HCPs. Multilevel, mixed-effects linear models were used to examine the association of HCP-related characteristics, including the implicit and explicit outcomes of HCPs, with those of their patients, their medication-taking behaviors, and disease activity. Of the 1,659 initially invited patients, 254 patients with RA (mean age 62.8 years, mean disease duration 11.8 years, and 68.1% of the patients were female) who were treated by 26 different HCPs agreed to participate in this study. The characteristics, attitudes, health-related associations, and beliefs about medicines of HCPs were not significantly associated with those of their patients, nor with their medication-taking behaviors or disease activity scores. This study demonstrated that the attitudes, health-related associations (as measured both implicitly and explicitly), and beliefs of HCPs were not significantly associated with the attitudes, beliefs, medication-taking behavior, and disease activity of patients with RA.