Purpose: The purpose of this study is to examine factors influencing medication adherence in patients with hypertension. Methods: This study carried out a secondary analysis of data from the 2008 Korean National Health and Nutrition Examination Survey (KNHANES). Stratified sampling was used to select a participant sample that was representative of patients with hypertension throughout the country. Using the SPSS/WIN 18.0 program, data were analyzed using descriptive statistics, $x^2$ test, t-test, and logistic regression. Results: Of the patients with hypertension, 8.8% had showed non-adherence to medication. Medication adherence was associated with age, spouse, Medicare insurance, number of other diseases, and current smoking status. The cases with older age, a spouse, Medicare insurance, higher number of other diseases, and no current smoking status showed significantly high medication adherence. Conclusion: Nursing interventions and further studies are needed to achieve high levels of medication adherence based on factors influencing medication adherence such as age, spouse, Medicare insurance, number of other disease, and current smoking status.