BACKGROUND: Adherence is the most important factor in determining Antiretroviral Therapy (ART) treatment success and long-term viral suppression. Nonadherence to ART led to the human Immunodeficiency Virus (HIV) related morbidity and mortality. Moreover, it intensifies the risk of the emerging drug resistant HIV strains. This study aimed to assess the level of ART adherence and to identify its predictive associated factors among people living with HIV/AIDS in Hara Town and its surroundings, North-Eastern Ethiopia. METHODS: An institutional facility based cross-sectional study was conducted from April-May 2017. A total of 454 individuals were on ART follow-up in the selected ART-clinic, and only 418 patients were recruited. Bivariate and multivariate logistic regression analyses were carried out to identify associated factors. Odds ratio and 95% Confidence Interval (CI) were calculated to determine the level of significance. RESULTS: The level of ART adherence in the study setting was 300 (71.8%). Participants who had not disclosed their HIV status to their families were 88% less likely to adhere to their ART medication than those who had disclosed their HIV status ((Odds ratio (OR): 0.12, 95%CI:0.05-0.58; p<0.001). On the other hand, participants who had not encountered drug side effects were 2.69 times more likely to adhere to their ART medication than those who had ever encountered drug side effects (OR: 2.69, 95%CI:1.27-5.05; p<0.001). CONCLUSION: A very low level of ART adherence was shown in the study population. It was below the recommended good adherence standard. Therefore, patients should get adequate and comprehensive ART adherence counselling before initiation ART treatment and during the follow-up time.