Objective: This study was to explore the association between having a usual source of care and adherence to medicines in patient with chronic diseases. Methods: The 2012 Korea Health Panel was used as a data source. We analyzed 4,418 respondents that were diagnosed with chronic diseases and utilized health care services. Non-adherence to medication, a dependent variable, was defined as "not taking the medicines that were prescribed for treating chronic disease" or "not following the direction for medication". Whether having a usual source of care or not was used as a key independent variable, which was defined as having a regular site or a regular doctor for medical test, treatment, and consultation. Sex, age, education level, marital status, income, the type of health insurance, the number of chronic disease and CCI (Charlson Comorbidity Index) were included as covariates in the analysis. We conducted a multivariate logistic regression. Results: Totally, 30 percent of respondents reported to experience non-adherence to medication. Having a usual source of care was significantly associated with lower non-adherence to medication regardless its type, which is a regular doctor (OR=0.61, 95% CI=0.53-0.70) or a regular site (OR=0.67, 95% CI=0.58-0.78). Furthermore, having a usual source of care was associated with both of medication persistence (OR=0.66, 95% CI=0.54-0.81) and compliance (OR=0.65, 95% CI=0.56-0.76). Conclusion: Our results showed the possibility that usual source of care is able to conduct a positive role in improving adherence to medication with better management of chronic disease.