The U.S. Food and Drug Administration (FDA) has initiated a historic transparency measure by releasing over 200 complete response letters (CRLs) issued to drug and biologic sponsors whose products were eventually approved. These letters, covering decisions made between 2020 and 2024, delineate deficiencies identified by the agency, ranging from safety and efficacy concerns to manufacturing and bioequivalence issues. While some sections remain redacted to protect proprietary information, this first batch aims to provide stakeholders with insight into the FDA's decision-making processes and common regulatory challenges. The FDA plans to continue expanding public access to CRLs in an effort to foster predictability and accountability within drug development.