Background: The prevalence of Human Immunodeficiency Virus (HIV) infection was 1.2% in the Democratic Republic of Congo, according to the Demographic Health Study report in 2014. In 2012, the severe failure rate to first-line ART in Kinshasa was estimated at more than 16%. Objective: The objective of this study is to determine the rate of clinical, immunological and virological failure in first-line treatment in Kinshasa. Methodology: At the 6th month of Antiretroviral Treatment (ART), 138 patients from a follow-up cohort of 8 centers in Kinshasa were received for paraclinical evaluations and analyses. The clinical and paraclinical parameters were recorded on the individual patient sheets as well as the survey forms. Clinical parameters, viral load and CD4 were evaluated at the 6th month of ART. Results: One hundred and thirty-eight (138) patients had returned for follow-up treatment, 81 women and 57 men. The average age of patients is 37 ± 12 years. The dominant age groups are those of 26 to 35 years and 36 to 45 years with 39 patients (28.3%) each, followed by those of 18 to 25 years (21.7%). One hundred and twenty-five (125) patients (90.5%) were in clinical stage 3 and 13 (9.5%) in clinical stage 4 according to the WHO classification. CD4 levels ranged from 98 to 1050 cells/mm³ and a median value of 560 cells/mm³. The median value of the patients’ VLs was 0.90 log₁₀ copies of RNA/ml with respective minimum and maximum values of 0 and 4.82 log₁₀ copies of RNA/ml. The virological failure rate was 24.6%. Conclusions: The rate of virological failure of first-line antiretroviral treatment of patients under treatment in Kinshasa is 24.6% for the year 2015.