The regulatory agency responsible for MDSAP (Medical Device Single Audit Program) registration for medical devices in the United States is the U.S. Food and Drug Administration (FDA).

The FDA oversees the regulatory requirements for medical devices sold in the U.S., and as part of the MDSAP, it participates in the audit process to ensure compliance with its regulations, specifically 21 CFR Part 820 (Quality System Regulation). MDSAP allows a single audit to meet the requirements of multiple countries, including the U.S., Canada, Brazil, Japan, and Australia. However, the FDA is the primary authority for medical device regulation in the U.S. under this program.