Achieving and maintaining viral suppression in young adults (18-24 years) living with HIV is challenging. Overall HIV viral suppression rates are lower in young as compared to older adults. Longitudinal data provide valuable insight on dynamics of viral suppression and variables of potential influence on HIV virological failure (VF), but is scarce in young adults living with HIV on combination antiretroviral therapy (cART). We evaluated longitudinal virological outcomes of behaviorally young adults (18-24 years) living with HIV in the Netherlands over a period of 15 years.We analyzed data from the Dutch national HIV database of 816 young adults living with HIV on cART in the Netherlands from 2000 to 2015. VF was defined as 2 consecutive detectable plasma HIV-1 viral load (VL) measurements > 200copies/ml. Generalized linear mixed model analyses were used to assess HIV VF over time and identify risk factors associated with VF.VF during the study follow-up occurred at least once in 26% of cases. The probability of experiencing VF decreased over the study period per calendar year (OR 0.78, 95% confidence interval [CI];0.72; 0.85). Factors significantly associated with VF were being infected through heterosexual contact (OR 5.20, CI 1.39;19.38) and originating from Latin America or the Caribbean (OR 6.59, CI 2.08;20.92). Smaller, yet significant risk factors for VF were being infected through a blood transfusion or a needle accident (OR9.93, CI 1.34;73.84, and having started with cART with a nadir CD4 count >500cells/μl (OR 11.36, CI 2.03;63.48).In our large cohort of young adults, the risk of VF has diminished over 15 years. Specific subgroups were identified to be at risk for suboptimal treatment.