Background: Tuberculosis is a major opportunistic infection among people living withrnHIV (PLWH). Antiretroviral Therapy (ART) was introduced in National AIDS ControlrnProgramme to reduce the morbidity and mortality among those affected with HIV/AIDS.rnEven though ART reduces tuberculosis (TB) incidence, risk of TB remains high after ARTrninitiation. However determinants of active TB among HIV patients on ART are not wellrndescribed in resource limited settings like Ethiopia.rnObjectives: To determine incidence and factors predicting active TB occurrence amongrnpatients enrolled in ART, in Zewditu Hospital, Addis Ababa.rnMethods: A five year institution based retrospective follow up study was conducted byrnchart review. All adult PLWHs newly enrolled on ART at Zewiditu hospital fromrnSeptember 11, 2009 to August 31, 2010, was identified from electronic data base andrnregister. And those who fulfilled the inclusion criteria were retrospectively followed forrndifferent periods in five years until March, 2015. The pretested data collection tool was usedrnin order to extract informationâ€™s from patient chart. Incidence rate of tuberculosis wasrncalculated. Cox proportional hazard regression model was used to identify predictors.rnResults: A total of 480 patients were followed and produced 1952.5 Person-Years (PY) ofrnobservation, and 70 new TB cases observed during the follow up period. The overallrnincidence density of TB was 3.59 per 100 PY. It was high (76.59/100PY) in the first year ofrnenrolment. The cumulative proportion of TB- free survivals was 90% and 80% at the end ofrnthe first and fifth years, respectively. After adjustment for potential confounders thernpresence of INH prophylaxis (AHR=0.49, 95%CI=0.26-0.94), baseline WHO clinical stagernIII or IV (AHR =2.37, 95%CI = 1.41-3.96), CD4 count