Patients with rheumatoid arthritis are at increased risk for cardiovascular disease. The prerequisites for reducing the risk of cardiovascular disease are adequate levels of knowledge and being aware of the risk. In this study, the levels of knowledge about cardiovascular disease among patients with rheumatoid arthritis and the perception were evaluated in relation to their actual 10-year risk of cardiovascular disease. This cross-sectional study of 200 patients with rheumatoid arthritis was conducted in a university-affiliated hospital in South Korea. The patients' actual risk of cardiovascular disease was estimated using the Framingham Risk Score. The most common risk factor was physical inactivity, with 77% of the patients not engaging in regular exercise. The patients lacked knowledge about the effects of physical inactivity and anti-inflammatory medication on the development of cardiovascular disease. Misperceptions about the risk of cardiovascular disease were common, i.e., 19.5% of the patients underestimated their risk and 41% overestimated. Hypertension, diabetes, obesity, and smoking were the most prevalent among the patients who underestimated their risk, and these same patients had the lowest level of knowledge about cardiovascular disease. This study demonstrated the rheumatoid arthritis patients' lack of knowledge about the effects of physical inactivity and anti-inflammatory medications on the development of cardiovascular disease, and their misperception of cardiovascular risk was common. As a preventive measure, educational programs about cardiovascular disease should be tailored specifically for patients with rheumatoid arthritis, and behavioral interventions, including routine exercise, should be made available at the time of diagnosis.