Abstract Motivation As new integrative methodologies are being developed to analyse multi-omic experiments, validation strategies are required for benchmarking. In silico approaches such as simulated data are popular as they are fast and cheap. However, few tools are available for creating synthetic multi-omic data sets. Results MOSim is a new R package for easily simulating multi-omic experiments consisting of gene expression data, other regulatory omics and the regulatory relationships between them. MOSim supports different experimental designs including time series data. Availability The package is freely available under the GPL-3 license from the Bitbucket repository ( https://bitbucket.org/ConesaLab/mosim/ ). Contact cmartinez@cipf.es Supplementary information Supplementary material is available at bioRxiv online.