Background: Human immunodeficiency virus (HIV) and tuberculosis (TB) are the principal global causes of death among patients with communicable diseases. Because of shared immune defense mechanisms, they are the primary cause of morbidity worldwide. However, little information was found regarding the magnitude of TB/HIV co-infection in the study area, in Northwest Ethiopia. Objective: The main aim of this study was to assess the prevalence of TB and HIV coinfection and associated factors among TB patients. Methods: All TB patients at Debre Markos Comprehensive Specialized Hospital were included from September 11, 2012 to September 10, 2016. Data were analyzed using SPSS version 22. Logistic regression was used to determine the associations between independent and outcome variables. Results: A total of 180 TB patients were enrolled. Pulmonary tuberculosis (PTB) accounted for 97/180 (53.9%), followed by extrapulmonary tuberculosis (EPTB) in 83/180 (46.1%). There were 164/180 (91.1%) new TB cases and 16/180 (8.9%) treatment failures, but no relapsing or defaulting cases were observed. Forty percent (72/180) of patients were coinfected with TB and HIV. The likelihoods of having TB/HIV co-infection were 3.2 and 2.1 times higher in PTB smear-positive and PTB smear-negative patients (AOR=3.2, 95% CI 1.4-8.1, p=0.006; and AOR=2.1, 95% CI 1.0-4.3, respectively, p=0.05), in comparison to EPTB. The rate of TB/HIV co-infection was 28/66 (42.4%) in 2013, 18/38 (47.4%) in 2014, 13/32 (40.6%) in 2015, and 13/44 (29.5%) in 2016. Conclusion: TB/HIV co-infection showed a decreasing trend in the past 2 years in the study area. TB/HIV co-infection is one of the most serious community health concerns in the study area. Therefore, TB/HIV collaborative activities should be implemented to reduce coinfection and its impact on the community.