ABSTRACT The expansion of HIV/ADIS epidemic has now become a burning issue globally. HIV infection has changed from a fatal condition to a manageable chronic illness mainly because of the event of antiretroviral therapy (ART). Whether or not ART treatment has shown significant clinical importance by meeting the goal of therapy, but still increases variety of deaths thanks to certain socio-demographic and clinical factors. The aims of this study was to spot determinant factors for the Survival time of adult HIV/ADIS Infected Patients under the follow-up of antiretroviral therapy (ART) at Debere Berhan clinic and model the progression of HIV/AIDS disease of a personal patient under ART follow-up supported CD4 level using Markov process processes. A retrospective study was undertaken on a sample of 301 HIV/AIDS patients were selected supported simple sampling technique for this study. Within the followed up period, 43 (14.3%) patients died and 258 (85.7%) patients were censored. From the whole death the bulk of death 13(4.3%) and 10(3.3%) deaths occurred within six months and twelve months of ART initiation, respectively. The Cox PH regression result indicated that the survival time of the HIV patient was significantly related with legal status, TB history, employment status, OIs, WHO stage, Regimen type, and Hemoglobin level. To determine Progression of HIV/AIDS Disease States, States of the stochastic process are defined by the seriousness of the sickness supported the CD4 counts. The states will be state I: CD4 count > 500 cells/μL, state II: 350 < CD4 count ≤ 500 cells/ μL, state III: 200 < CD4 count ≤ 350 cells/ μL, state IV: CD4 count ≤ 200 cell/ μL and Death. The primary four states are named pretty much as good states and Death were bad or absorbing state. There have been transitions between good states to the following worse state. From the above four state, in state IV there have been high number of deaths compared to others state. This means that the probability of dying increase with decreasing CD4 counts over time.