Summary Background: Antiretroviral therapy (ART) cannot cure HIV infection because of a persistent reservoir of latently infected cells. Approaches that force HIV transcription from these cells, making them susceptible to killing - termed ‘kick and kill’ - have been explored as a strategy towards an HIV cure. RIVER is the first randomized trial to determine the impact of ART alone versus ART plus ‘kick-and-kill’ on markers of the HIV reservoir. Methods: RIVER (Trial registration: NCT02336074) was an open-label, multicenter, 1:1 randomized controlled trial of ART-only (control) versus ART plus the histone deacetylase inhibitor vorinostat (the ‘kick’) and replication-deficient viral vector vaccines encoding conserved HIV sequences ChAdV63.HIVconsv-prime, MVA.HIVconsv-boost T-cell vaccination (the ‘kill’) (ART+V+V; intervention) in HIV-positive adults treated in recent HIV-infection. The primary endpoint was total HIV DNA in peripheral blood CD4+ T-cells at weeks 16 and 18 post-randomization. Secondary endpoints included safety, alternative measures of the HIV reservoir including quantitative viral outgrowth, HIV-specific T-cell frequencies, and CD8+ T-cell mediated viral inhibition. Findings: Between December 2015 and November 2017, 60 HIV-positive male participants were randomized (computer-based and stratified by time since diagnosis; 30 participants in each trial arm) and completed the study interventions, with no loss-to-follow-up. There were no intervention-related serious adverse events. Mean total HIV DNA at weeks 16 and 18 was 3.02 log10 copies HIV DNA/106 CD4+ T-cells in the control and 3.06 log10 copies HIV DNA/106 CD4+ T-cells in the intervention arm, with no statistically significant difference (mean difference of 0.04 (95%CI -0.03, 0.11) log10 total HIV DNA copies/106 CD4+ T-cells (p=0.26)). Interpretation: This ‘kick-and-kill’ approach conferred no significant benefit compared to ART alone on measures of the HIV reservoir. Although this does not disprove the ‘kick and kill’ strategy, for future trials significant enhancement of both ‘kick’ and ‘kill’ agents will be required.