This paper measures high medical expenses in ten developed countries, both overall and by income and age, providing some of the best evidence to date on the extent of high medical spending across and within countries. Using comparable household-level data on out-of pocket (OOP) medical expenditures made available through the Luxembourg Income Study (LIS), we measure high spending when it exceeds a threshold share of household income. The results show that the U.S. is far from alone in its failure to protect individuals from large medical expenses. In five of the other nine countries, one-quarter or more of poor households devoted at least 5 percent of household income to OOP expenses. The rate of high spending in the US is similar to Japan's, but below that in Russia, Poland, Israel, and Switzerland. The high levels of exposure to large medical expenses in most countries indicates the need to develop robust measures of excessive spending that capture both future risk as well as past burdens.