A Principal Investigator (PI) is the individual responsible for the overall conduct of a clinical trial at a research site, including participant safety, protocol compliance, and data integrity.
The PI oversees informed consent, delegation of study tasks, supervision of the research team, and adherence to regulatory requirements. Sponsors and IRBs rely on the PI to ensure deviations are addressed, safety events are reported, and study records are complete and accurate. PI accountability is central to oversight frameworks and inspection outcomes. Strong PI leadership improves participant protections and strengthens trial quality.