[영문]This article analyzes the effect of gatekeeper and network restrictions on use of healthcare services using simulationbased estimation methods. Data from the Community Tracking Survey 1996?1997 show significant evidence of selection into plans with gatekeeper andor network restrictions. Enrollees in plans with networks of physicians have fewer officebased visits to nonphysician medical professionals, but more emergency room visits and hospital stays. Individuals in plans that require signups with a primarycare provider have more visits to nonphysician providers of care, more surgeries and hospital stays but substantially fewer emergency room visits. Enrollees of plans that do not pay for outofnetwork services have more officebased and emergency room visits, but less surgeries and hospitalizations