To assess patients' reactions to a mandatory second surgical opinion program and to measure the accuracy of communication between these patients and their physicians, questionnaires were sent to New York City municipal employees, retirees, and dependents who had received second-opinion consultations. The most frequent reactions, among 902 respondents, were that the consultations provided reassurance (59%), helped in deciding whether to proceed with surgery (49%), and provided a chance to ask important questions (29%). Relatively few patients felt that the program caused anxiety (12%) or confusion (5%). Patients were generally pleased with the administrative aspects of the program but less satisfied with the consultant physicians they had seen. Twelve percent of patient-physician pairs disagreed about the advice that had been communicated in their second-opinion consultation visits. Nonconcordance rates varied greatly with the nature and complexity of the advice rendered and were higher among patients who stated that their consultants' explanations were not thorough and understandable. In addition to their cost-containment functions, mandatory surgical second-opinion programs can be supportive and informative. Systematic feedback from patients can be used to enhance these strengths, to correct programmatic deficiencies, and to improve the accuracy of communication.