OBJECTIVES: This paper examines which families bear the heaviest financial burden from recent changes in cost-sharing provisions of employment-based health insurance among different socioeconomic and health statuses characteristics.  METHODS: The data source for this study is the Medical Expenditure Panel Survey (MEPS), a nationally representative household panel survey conducted by AHRQ in 2001 and 2005. We apply semi-log regression model to identify factors that help to explain the variation in family out-of-pocket spending (FOOPSPD) and quantile regression to describe how FOOPSPD has changed throughout the out-of-pocket spending distribution and thus to assess the effectiveness of risk protection from holding employment-based health insurance. Additionally, a quantile regression is used to decompose the difference in FOOPSPD distribution into changes in family characteristics and changes in structural factors.  RESULTS: Between 2001 and 2005, average FOOPSPD had significantly increased by 22%. Econometric findings showed that having one more health conditions increased FOOPSPD by up to 11%. Additionally, the biggest increase in FOOPSPD occurred among families who were in the top quantiles of the FOOPSPD distribution with certain health conditions. Among 11 major high-cost health conditions, having COPD or asthma and/or hypertension were the two key conditions that triggered the biggest increases in FOOPSPD burdens. The results from the decomposition analysis revealed that more than 80% of changes in FOOPSPD were associated with the structural changes. CONCLUSIONS: Families who relied more on health care because of one or more family members’ existing health conditions were most affected by changes in cost sharing during the study period. In addition, decreases in the “return” to risk protection from holding private health insurance, in terms of increased exposure to premium payments and out-of-pocket medical spending, occurred primarily for families who spent the least and the most out-of-pocket for medical care experienced greater increase in FOOPSPD.