Complaints related to FDA-regulated clinical trials should be reported to the office responsible for the product involved:

Biologics studies (including gene therapy and vaccine studies):
Call 240-402-8010
Fax 301-595-1245
Email: ocod@fda.hhs.gov
(CBER)

Clinical and preclinical studies involving products regulated by the Center for Food Safety and Applied Nutirition (CFSAN):
Call 240-402-1757
FAX 301-436-2668
Email: yuguang.wang@fda.hhs.gov
(Bioresearch Monitoring Program, Office of Center Director, CFSAN)

Drug studies:
Call 301-796-3150
Fax 301-847-8748
Email: CDER-OSI-GCPReferrals@fda.hhs.gov
Office of Scientific Investigations (CDER)

Medical Device studies:
Call 301-796-5490
Fax 301-847-8136
Email: BIMO-CDRH@fda.hhs.gov
(Division of Bioresearch Monitoring, Office of Compliance, CDRH)

New animal drug studies:
Call 240-402-7001
Fax 240-276-9241
Email: CVMBIMORequests@fda.hhs.gov
(Premarket Compliance and Administrative Actions Team, CVM)

Tobacco studies:
Call 240-402-7970
Email: CTP-BIMO@fda.hhs.gov
Office of Compliance and Enforcement (CTP)