The association of dysregulated microRNAs (miRNAs) and diseases has been shown in a variety of studies. Here, we review a resource denoted as PhenomiR, providing systematic and comprehensive access to such studies. It allows machine-readable access to miRNA and target relations from these studies to study the impact of miRNAs on multifactorial diseases across many samples and biological replicates. We summarize the PhenomiR data structure and its content and show how to access the database and use it in everyday miRNA profile analysis using the R language.