The US Food and Drug Administration (FDA) has published a new guidance document to support the use of Bayesian methods in clinical trials of drugs and biologics.[1] This paper focuses on incorporating Bayesian applications into primary inference about drug efficacy and safety.[1] Bayesian approaches combine data from a clinical trial with relevant prior information to create a new distribution for inference.[1] FDA Commissioner Marty Makary called the change a leap forward from the traditional frequentist model of data analysis.[1] The goal is to improve the design and analysis of clinical trials, thereby reducing drug development time.[1] The document fulfills FDA's Prescription Drug User Fee Act (PDUFA) VII obligation and is available for public comment.[1] Bayesian methods are particularly useful for studies focusing on rare or pediatric diseases with smaller numbers of patients.[1]