The microRNA (miR)-mRNA axes involved in oxidized low-density lipoprotein (ox-LDL)-induced vascular smooth muscle cells (VSMCs) proliferation/apoptosis imbalance need to be investigated in more detail.To investigate the function and any relevant changes to miR-mRNA axes in the ox-LDL-induced proliferation/apoptosis imbalance in VSMCs.Human VSMCs were cultured and treated with ox-LDL in vitro. The differentially expressed (DE) miRs and mRNAs in VSMCs following 48-h ox-LDL treatment were detected using RNA sequencing. Candidate miRs and mRNAs were further selected, based on comprehensive bioinformatics analysis. Changes in the expression of candidate miRs and mRNAs in ox-LDL-treated VSMCs were confirmed with quantitative real-time polymerase chain reaction (RT-qPCR) and western blot. The inhibitory effect of candidate miRs on mRNAs were demonstrated using a dual luciferase reporter assay. The functional role of candidate miRs and mRNAs on proliferation, cell cycle and apoptosis of VSMCs were estimated using cell couting kit-8 (CCK-8) and flow cytometry assays, respectively.The RNA sequencing data indicated that 577 mRNAs and 81 miRs were significantly upregulated in VSMCs following ox-LDL treatment. Gene function and pathway enrichment analysis suggested that the DE-mRNAs and miRs participate in the regulation of proliferation, cell cycle and apoptosis. Increased expression of DLX5 with decreasing miR-124-3p levels were confirmed in ox-LDL-treated VSMCs. The miR-124-3p could inhibit the DLX5 level by binding the 3' UTR of DLX5 mRNA. Functional analysis showed that the alteration of miR-124-3p/DLX5 expression mediated the effect of ox-LDL on VSMCs proliferation/apoptosis imbalance.The ox-LDL affects the VSMC proliferation/apoptosis balance via the miR-124-3p/DLX5 axis, which results in VSMC hyperproliferation. The miR-124-3p/DLX5 axis might serve as a therapeutic molecular target to reverse the effect of ox-LDL and prevent atherosclerosis (AS) development and progression.