- Background: Second opinion (SO) is common in medical practice and can reduce unnecessary risks and costs. To date, there is no population-based estimation of how many people seek SOs and what the characteristics of second-opinion seekers are. Objectives: To estimate how many people seek SOs, and what the characteristics of second-opinion seekers are. Methods: We conducted both a medical records analysis (n=1,392,907) and a cross-sectional national telephone survey with a representative sample of the general Israeli population (n=848, response rate=62%). In the medical records analysis, we linked consultations with specialists at community secondary care and private consultations using claims data. We developed a time-sensitive algorithm that identified potential SO instances. In both methods, we predicted the characteristics of second-opinion seekers using multivariate logistic regressions. Results: The medical records analysis and the survey findings were highly consistent, and showed that about sixth (14.9% in the medical records vs. 17.2% in the survey) of a general population sought a SO, mostly from orthopedic surgeons. Women, native-born, and established immigrants, people living in central urban areas or close to central urban areas, people with chronic conditions, and those who perceived their health status as not very good, were more likely to seek SOs than others. Conclusions: A considerable amount of people sought a SO. Certain patient profiles tended to seek SOs more than others. Such utilization patterns are important to devise policy regarding SOs, due to their implications on expenditure, policy, clinical outcomes, and patient satisfaction.