Background: Despite the large number of TB patients on ART in Ethiopia, their mortality remains high. This study reports the effect of TB on HIV related mortality and determinants of TB/HIV co-infection related mortality. Methods: A longitudinal study design was employed as part of the Advanced Clinical Monitoring of ART (ACM) in Ethiopia. All patients started on ART at or after January 1, 2005 were included. Survival analysis was done to compare survival patterns of HIV patients with TB against HIV patients without TB. In addition, determinants of survival among TB/HIV co-infected patients were analyzed. Adjusted effects of the different factors on time to death were generated using Cox-proportional hazards regression. Results: A total of 3,889 patients were enrolled in the ACM study, of which 355 TB cases were identified, making the crude prevalence 9% (95% CI 8.3 – 10.2). Overall, incidence of TB was 2.2 (95% CI 1.9-2.4) per 100 person-years. TB was highest in the first 2 months and declined with time on ART to reach 1 per 100 person years after 24 months on ART. TB was significantly associated with mortality among HIV patients on HAART (AHR 2.0, 95% CI 1.47-2.75). Male gender was associated with mortality among TB/HIV co-infected patients.Conclusion: Tuberculosis plays a key role in HIV associated mortality. Targeted interventions which can keep patients free of TB in the early stages of their treatment are required to reduce TB related mortality.  Key Words: Tuberculosis, Antiretroviral therapy, Mortality