Appropriate drug information is essential in pharmaceutical care practice. In recent years, educating patients with their prescription and drug therapy is becoming an increasingly important aspect of health care. Appropriate drug information has been shown to improve patients’ adherence to their medication and the results of pharmacotherapy. The purpose of this study was to study patients’ sources of drug information and their preferences in Korea. This study was a 11-questionnaire survey conducted from February 8, 2010 to February 25, 2010. Major sources of drug information used by respondents, proportions of respondents who received drug information on administration, dosage, indication, or warnings and precautions, sources of drug information which patients prefer, and the reasons of their preferences were studied. Of the 303 respondents, the most common sources of drug information were pharmacists (29.7%), doctors (23.8%), and the Internet (17.2%). There were significant differences according to sources of drug information in proportions of respondents who received drug information on administration, dosage, indication, or warnings and precautions. Patients preferred pharmacists as a drug information source the most (38.9%), and the reasons were reliability (72.0%) and easy to use (28.0%). Based on the results of this study, further studies should be conducted to establish the best way to provide appropriate drug information for patients and improve the results of pharmacotherapy.