BACKGROUND፡ Ethiopia has been motivated to achieve a goal of “appointment spacing model approach care.” However, little has been documented on the predictor of mortality and challenges of sustainable HIV care.  Therefore, the aim of this study was to determine predictors of mortality among adult people living with HIV/AIDS on antiretroviral therapy (ART).METHODS: A retrospective cohort study was conducted on 676 adult people living with HIV who enrolled to ART clinic from September 01, 2012 - August 30, 2016. Multivariable Cox Regression analysis was done where adjusted hazard ratio (AHR)with corresponding 95% confidence interval (CI)  at P value ≤ 0.05 cut of point was used to identify predictors of mortality.RESULTS: The total person-time contributed was 28,209 person-months with an overall mortality incidence rate of 11 per 1000 person-months observation. The cumulative mortality incidence among females over the study period was 16.8% (64/382). Severe undernourishment and moderate malnutrition at baseline, younger age, female sex, single, divorced, illiterate, lack of disclosure, advanced WHO clinical stage, seeking treatment outside catchment area, rural residence and immunological failure were found to be independent predictors of mortality.CONCLUSIONS: Poor nutritional status at baseline, advanced stage of HIV disease, occurrence of treatment failure, female sex, substance abuse, lack of social support, immunological failure, clinical failure, and younger age, low level of education and poor physical access to healthcare facility were found to be important predictors of mortality. Intervening, those factors as routine and part of the appointment spacing model care can improve survival of PLWHA.KEYWORDS: Adult, Appointment Spacing Modals, ART, PLWHA, Predictors, Jimma zone.