Background: Opportunistic infections are diseases that cause infections in individuals whose immune systems are compromised. Morbidity and mortality in HIV disease are due to immunosuppression leading to life-threatening opportunistic infections during the natural course of the disease. Human immune virus (HIV/ADIS), with which 36.7 million people were living and 2.1 million infected at the end of 2016, has been a major health problem throughout the world. The commonly reported opportunistic diseases in sub-Saharan Africa among HIV patients are Candidiasis, Pneumocystis carinii pneumonia, disseminated Mycobacterium avium complex infection, Cryptococcus, Kaposi sarcoma, herpes zoster, and tuberculosis Methods: Institution based cross-sectional study design was applied based on patient record cards. The sample size was 384 and samples were taken by using simple random sampling method. Data were collected by a pre-tested checklist from the medical records of patients with 100% response rat. Data were entered and analyzed for descriptive and logistic regression models by SPSS version 26.0 statistical software. The result declared as statistically significant at p < 0.05. Result: The overall Magnitude of opportunistic infections was 51.3%[95% CI: 46.4-56.5]. The major identified opportunistic infections were recurrent bacterial pneumonia 79 (20.6%), tuberculosis (pulmonary &/or EPTB) 59 (15.4%), candidiasis (Oral & esophageal) 56(14.6%) herpes zoster 38 (9.9%), and Chronic diarrhea 33 (8.6%). On multivariate analysis, age group of 30-39 [AOR=2.70, 95% CI: 1.09, 6.67] and Being in baseline WHO stage of II, III or IV had 8.2 times [AOR=8.20, 95% CI: 3.63, 18.51], 29.19 times [AOR=29.19, 95% CI: 12.40, 68.71] and 22.95 times [AOR= 22.95, 95% CI: 5.32, 99.01] increased risk of developing OI respectively. Conclusion: In this study, the overall Magnitude of OIs is high (51.3%) when compared with other studies. This suggests that OIs remain a challenge in RVI patients in Ethiopia despite taking ART. Health officials and clinicians need to give attention to the strengthening of the provision of ART with prophylaxis on early WHO stage. Community awareness creation about the virus should also be facilitated. Keywords: HIV; Opportunistic Infections; Antiretroviral Therapy