By randomizing the insurance premium for the SKY micro-health insurance program in rural Cambodia, allows casual effects of health insurance on economic, health care utilization, and health outcomes to be estimated. In conclusion, SKY insurance has its greatest impact on economic outcomes. SKY also changed health-seeking behavior, increasing the use of covered public facilities and decreasing the use of uncovered unregulated care, but had no detectable impact on preventive care. As expected due to low statistical power, there were statistically limited impacts on health.