Physicians report that concern about regulatory investigation negatively influences their prescribing of opioid analgesics. The views of medical regulators about the legality of prescribing controlled substances for pain management were studied in 1991. However, little is known about whether these views have changed in light of increased emphasis on pain management and educational programs for state medical boards. Two studies that examined this issue are described. In Study 1, a 1997 survey of state medical board members was compared to results obtained in 1991 to evaluate differences in knowledge and perceptions about opioid analgesics. Important changes were observed over time, particularly regarding characteristics of "addiction" and the legality of prolonged prescribing of opioids. For Study 2, a longitudinal survey was conducted of medical board members who participated in five workshops about pain management and regulatory policy. Results revealed significant and sustained changes in attitudes about the incidence of iatrogenic addiction when using opioids to treat pain, the analgesic and side-effect properties of opioids, and the perceived legality of prescribing opioids. Recommendations for reducing concerns about regulatory scrutiny are presented, including the need for a more intensive education program, increasing the rate of adoption of new state medical board policies, and improving communication between regulators and clinicians.