Objective: To compare the impact of mandated IVF insurance coverage on ET practices and resulting multiple pregnancy rates. Design: Retrospective analysis of all fresh, nondonor IVF cycles performed in the United States in 2006. Setting: United States. Patient(s): A total of 91,753 fresh, nondonor IVF cycles in the United States. Intervention(s): None. Main Outcome Measure(s): Pregnancy rate, live-birth rate, embryos transferred, multiple pregnancy rate. Result(s): Overall, nonmandated states had a significantly higher pregnancy rate (38.8% vs. 35%) and live-birth rate (32.2% vs. 29.1%) than mandated states. Nonmandated states also had a significantly higher twin rate (28.1% vs. 26%) and triplet rate (3.9% vs. 3.4%). The average number of embryos transferred was also significantly higher in nonmandated states (2.6 vs. 2.2). These findings were more pronounced in the <35 and 35-37 age groups. Conclusion(s): In the last 8 years, despite a reduction in the average number of embryos transferred and multiple pregnancy rates, there is a continued association between mandated IVF coverage, the transfer of fewer embryos, and lower rates of multiple pregnancies and births, particularly in the younger age groups. (Fertil Steril (R) 2011; 95: 964-9. (C) 2011 by American Society for Reproductive Medicine.)