Diabetes Mellitus is a growing public health problem worldwide as well as in Sri Lanka. Most individuals are likely to face barriers in take care of Diabetes Mellitus which is adhering to drug compliance. Poor compliance may associate with several factors. Numbers of patients with Diabetic Mellitus were high in Batticaloa district. Therefore it was essential to conduct a study among diabetic patients to assess the factors influencing on poor drug compliance. A cross sectional study was conducted among 150 Diabetic Mellitus patients in the Diabetic Clinic at the Teaching Hospital, Batticaloa. Patients, above 35 years and who presented the clinic during data collection were included in this study. Data were collected by using an interviewer administered questionnaire. Pre-test was conducted. Data were analyzed to assess the influencing factors of poor drug compliance. Among the respondents 57.3 % (n=86) were females; 42.7 % (n=64) were diagnosed with diabetic mellitus for 1 to 5 years; 68% (n=102) were reported that the reason for skipping medication is fear of side effects; 38% (n=57) were not attending the clinic due to their work schedule; 31.3 %( n=47) were not taking drugs because of forgetting. Rate of poor oral anti diabetic drugs compliance of patients in Batticoloa district was high. Level of education played an important role in poor adherence to medical advice. Patients should be encouraged to use anti diabetic drugs and regular awareness should be created regarding the benefits of using them to prevent the intentional poor oral drugs compliance.