Diabetes mellitus is a growing global health problem that affects individuals of all ages. Lack of adherence to anti diabetic medication causes suboptimal blood sugar control among patients with diabetes and can lead to treatment failures, accelerated development of complications and increase, the objective of the study was to assess the magnitude of adherence of diabetic patients toward their anti- diabetic medication at Halibet Regional Referral Hospital. A descriptive, crosssectional quantitative approach was used. 205 samples was determined using Crecy and Morgan formula and convenience non probability sampling technique was used. Data was entered into excel then exported to SPSS V-20 for data analysis and it was analyzed used Chi square test. A total of 205 study participants were interviewed with response rate of 100%. The level of adherence was found to be 86.31%. Factors found to be significantly associated for non-adherence were, duration of diabetes (P-value =0.001), lack of health education about DM and its medications (P-value=0.004), complains of multiple medication (P-Value= 0.018), forgetfulness (P-value=0.000), lack of monitoring instrument, Glucometer) (p-value=0.06). At conclusion, majority of respondents 86.3% in this study were found to be adherent to their anti diabetic medications. Duration of diabetes, health education about DM and its medication, presence of co-morbid disease, forgetfulness, monitoring of blood glucose were significantly associated with adherence to anti- diabetic medication