Genomic methods are a molecular window into the dysregulation of genes and how they may impact human health and disease. They vary widely in how they interrogate the genetic blueprint including epigenetic changes like DNA methylation, or gene expression. They have become variously available and accessible and have become standard methods in oncology or other diseases. This has led to applications of predictive claims for response or progression as companion diagnostics to anti-oncologic therapies or screening for disease whose symptoms are yet to present. The explosion of these technologies has led to renewed efforts by the US Food and Drug Administration to regulate molecular diagnostics. This chapter describes regulation of genomic diagnostics technologies, both for the innovator and the regulator alike.