Pharmacometric tools for common data preparation tasks, stratified bootstrap resampling of data sets, NONMEM control stream creation/editing, NONMEM model execution, creation of standard and user-defined diagnostic plots, execution and summary of bootstrap and predictive check results, implementation of simulations from posterior parameter distributions, reporting of output tables and creation of a detailed analysis log. All functions are considered stable unless marked as beta. (MIfuns package requires plyr, reshape, XML, and fork (nix only) R packages.) MIfuns is an active, open-source project of Metrum Institute (http://metruminstitute.org).