Background: Viral load is the key indicator of the effectiveness of antiretroviral treatment in HIV patients. Study aimed to determine antiretroviral treatments failure rates and associated risk factors among HIV-infected adult patients in Congo. Methods: Data from the Congolese AIDS and Epidemics Control Council were combined to create a historical cohort. Patients were followed up between 2003 to 2017. Mixed logistic regression was used to identify treatment failure associated-factors. Intercooled Stata 10 (StataCorp LP, College Station, Texas, USA) software packages was used for analysis. Results: Over 14 years of follow-up, a total of 25,500 visits for 6391 adult patients were reported. Among them, 88% i.e. 22,328 visits (for a total of 6127 patients) were visits with treatment failure. In the multivariate analysis, being aged >26 years, having primary education level, being student, others nationality, unspecifiedmarital status and being worker in informal sector were found associated with a higher risk of treatment failure. Conversely, being pensioners, receiving second line therapeutic protocols and having good adherence to treatment were found significantly associated with a lower risk of treatment failure. Conclusion: Antiretroviral treatments failure among HIV-treated patients is common in Congo. Developing treatment adherence-centered interventions with focus in patients who have low socio-economic status needed to reduced treatments failure. As treatment failure is not only determined by individual factors, psychosocial supports and availability of antiretroviral drugs needs to be taken into account.