HIV infection and AIDS are majorpublic health challenges in Nigeria, a country with one of the highest rates of new infection in sub-Saharan Africa and the second largest HIV epidemic in the world.Non-adherence to medication and defaulting from treatment are the two major challenges faced by anti-retroviral therapy (ART) programs in resource-constrained settings. This study was undertaken to determine the rate and predictors of adherence to medication and retention among people living with HIVin Enugu State, Nigeria. This was a cross-sectionalretrospective study conducted among adults living with HIV(PLHIV) receiving ARTs in eightcomprehensive health facilities in Enugu, Nigeria. We used self-reported adherence and recorded clinic visits to assess adherence and retention, respectively. Descriptive statistics (frequencies, proportions, mean and standard deviation) and regression analysis were then conducted to identify the association between adherence, retention and demographic and health-related factors. The mean age of respondents was 38.5±9.8 years. Predictors of good adherence to medication includedbeing male(adjusted odds ratio [AOR]:2.08; 95% confidence interval [CI]:1.12-3.85), having been on anti-retroviral medications for more than 5 years (AOR:1.92; 95% CI: 1.17-3.16), the non-consumption of alcohol(AOR: 3.67; 95% CI: 2.01-6.70), not usingtraditional medicine (AOR: 2.76; 95% CI:1.33-5.73) and having a baseline CD4count exceeding 500 cells/µl (AOR: 5.67; 95% CI: 1.32-24.32).Adequate retention was predicted by being resident in the urban area (AOR: 1.90; 95% CI: 1.17-3.06). Being away from home (41.8%) and forgetfulness (35.0%) were reported as the major reasons for missing medication. The rates of adherence and retention found in this study were similar to those reported forother resource-limited settings. Health education and behavioural modification interventions should be intensified to reduce the consumption of alcohol and the use of traditional medicine by people living with HIV. Identifying other factors may help to design effective strategies to ensure that people living with HIV adhere to their medications and remain in care.