Introduction: In Senegal, the decentralization of Health Care Centers has contributed significantly to the intensification of antiretroviral treatment. However, Care providers are still facing the treatment optimizing challenge. Objectives: To determine the prevalence of virologic failures of PLHIV monitored in a decentralized Health care center and to determine associated factors. Patients and Methods: This is a cross-sectional descriptive and analytical study of PLHIV, aged 18 years and over, on first-line treatment, monitored onsite from February 1st to December 31st, 2018. A data collection form was completed from medical records (clinical, immuno-virologic and evolutionary). Any VL > 1000 cp/ml after 6 months of antiretroviral therapy (ART) was considered as virologic failure. Data were captured and analysed using the EPI INFO 2002software. Chi-square test and the Fisher test were used to compare the proportions; a value of p ≤ 0.05 was considered significant. Results: 331 patients were treated with HIV-1 profile in 89% of cases. A proportion of 55% was married and 97% came from rural areas. 80% were either not or poorly educated. The median of age was 44 ± 11 years with a F/M ratio of 3.4. At baseline, 56% were symptomatic at stage 3 or 4 of WHO. They had severe immunosuppression with a median CD4 count of 217 ± 187 cells/mm 3 , the viral load was detectable in half of the patients with a median VL of 97,000 cp/ml ± 70,569. The antiretroviral regimen combined 2 NRTIs with 1 NNRTI in 88% of cases.