Warning Letters issued by the Food and Drug Administrations (FDA) Bioresearch Monitoring Program provide insight into data integrity issues and other research misconduct in the premarket side of the pharmaceutical industry. This study presents an analysis of inspections and warning letters related to clinical investigators, institutional review boards (IRBs), sponsors of clinical studies, good laboratory practice (GLP) laboratories, and bioequivalence studies. The most common violations found included failing to follow and maintain procedures and poor documentation practices. Although the number of warning letters has decreased over the past decade and inspection results have been improving, there are still significant data integrity and other regulatory compliance issues found in the premarket side of the pharmaceutical industry.