Background: Drug adherence is the most significant in the progression of diseases. Thus, this study aimed to assess adherence and associated factors among seropositive people received treatment. Methods: Facility-based cross-sectional study was conducted in Jimma town public health facility from March to April 2019 on 385 selected participants. Systematic sampling technique was used to select study participants. The data were entered using Epi-data version 4.1 and analyzed by SPSS version 20 software. Variables with p-value of less than 0.25 in binary logistic regression were entered into the multivariable logistic regression to control cofounding A significance level of less than 0.05 was used in the final model to judge statistical significance. Results: The magnitude of adherence to antiretroviral treatment was 69.4%. Food security (AOR = 1.75 (95% CI;(1.01-3.0), substance abuse (AOR = 0.55 (95% CI;(0.32-0.96), Didn’t take other medications (AOR = 2.11(95%CI;(1.15-3.87), Good relationship with providers (AOR = 3.35(95%CI;(1.55-7.2), and irregular appointment (AOR = 0.19(95%CI; (0.11-0.34) were significantly associated. Conclusion: The magnitude of adherence to Anti-retroviral therapy was low compare to WHO. Food security, substance abuse, use of other medication, relationship with the health care providers, and irregular appointment were the factors associated. Treatment. Therefore, it is recommended that patients and health care workers enhance Antiretroviral Treatment adherence.