This study is intended to investigate medication compliance and polypharmacy of the diabetic patients by age group in order to determine the major factors that influence their compliance. 198 ambulatory diabetic patients were interviewed, and the sample was divided into three groups based on the age: Young age group under 55, Borderline age group between 55 - 65, Old age group over 65. According to the study results, medication compliance for the old age group was 72.6% whereas 85.1% for the young age group. Medication compliance significantly decreased as the age of the patients increased. Also the degree of polypharmacy, the rate which patients take more than 6 prescription drugs, was 45.9% for the old group, whereas 31.2% for the young group. As the most important factor of polypharmacy, the number of doctors was statistically significant. With regard to prescription factors related to medication compliance, the amount of prescribed medication is statistically significant between the compliance group and non-compliance group. In addition, the amount of information provided to patients by pharmacists was determined to be a very significant factor. Also the level of ease in understanding the medication instructions varied significantly between the compliance group and the non-compliance group. In light of the empirical data and results for the diabetic patients, it is necessary to develop and implement various programs to improve medication compliance and to decrease the level of polypharmacy among the elderly, or "old", diabetic patients. patients.