BACKGROUND: Few studies have examined the effects of Institutional Review Board (IRB) requirements to contact potential research participants. OBJECTIVE: To examine the association between requirements to contact potential research subjects and participation rates in a multisite health services research study. RESEARCH DESIGN, SUBJECTS: Prospective observational study of survey participation by 2673 individuals with diabetes and 1974 individuals with congestive heart failure treated at 15 clinical sites in the United States that had implemented a quality improvement intervention. MAIN OUTCOME MEASURES: Telephone survey response rates. RESULTS: Of 15 IRBs, seven required sites to obtain authorization from participants to release contact information to the study team. Five required oral and two required written advance permission. The response rate was 58% (913/1571) at sites where no advance permission was required, 39% (989/2530) from sites that required oral advance permission and 27% (145/546, P <0.001) at sites requiring written advance permission. Although 85% of eligible participants contacted directly by the study team consented to complete the survey, only 43% of individuals at sites requiring written advance permission allowed the release of contact information to the study team. CONCLUSIONS: Many potential participants did not grant advance permission to be contacted by the study team. Requiring advance permission reduced participation rates, especially at sites requiring written authorization.