Background:With the federal scale-up of antiretroviral therapy (ART) in Ethiopia, survival and quality of life for people with HIV/AIDS has increased. However, some patients do not respond to antiretroviral therapy (ART). Failure to suppress viral replication leads to increased morbidity and mortality, making early diagnosis of treatment failure is imperative for the reduction of negative outcomes for patients. Objective: The aim of this study was to characterize the success to failure patterns and determine predictors of Immuno-virologic outcomes among Adult HIV/ AIDS patients receiving Highly Active Anti-retroviral Therapy in FelegeHiwot Referral Hospital Northwest Ethiopia 2017. Methods: A retrospective cohortstudy design was followed at antiretroviral Therapy follow up clinic of FelegeHiwot Referral Hospital. Data were extracted from medical records of adults commenced on HIV treatment since January 01, 2013using a standardized extraction tool. The data were entered in Epi-info version7, and exported to SPSS Version 23 for analysis. In descriptive analysis, variables were summarized using frequencies, and summery measures. Results:Among the total of 350 participants, 61.1% were females, 71.1% were younger than 40 years. About 91.7% were orthodox Christian in religion & 82.3% were urban residents. The number of study participants who resulted in immune - virologic failure were 176 (50.3%) from which 107 were those who started medication late with baseline CD4 count less than 100 CD4 per mm3.Patients with shift in ART were at higher risk of developing Immuno-virologic failure (AHR =2.164, 95% CI: 1.447–3.171) than patients stayed on baseline ART regimen. In addition, Baseline CD4 count and types of ART regimen 2 significantly associated with the immune-virologicfailure. Conclusion: With a maturing HIV treatment program in Ethiopia, monitoring of patients on first line treatment to identify those who are more likely to develop immune-virologic failure is highly crucial.Clinicians should exert their effort to maintain patients on their initial regimen for as long as possible duration with appropriate care and close follow-up. Key words: HIV, ART, Immuno-viorologic outcome, Survival Analysis, Retrospective Cohort.