Men have higher death rates than women, but women do worse with regard to physical strength, disability, and other health outcomes, the so called malefemale health-survival paradox. The paradox is likely to be due to multiple causes that include biological, behavioral, and social differences between the sexes. Despite decades of research on the male-female health-survival paradox, we still do not fully recognize whether behavioral factors explain most of the gender gap or whether biological and social differences contribute more substantially to the explanation of the sex differences in health and mortality. Little work has been done to investigate the magnitude of sex differences in healthy life expectancy and unhealthy life expectancy, as well as to examine the contribution of mortality and disability levels to the sex gap in health expectancy. The five selected works presented at the Réseau Espérance de Vie en Santé (REVES) Meeting 2009 in Copenhagen, and published in this issue, provide new insights into sex differences in health expectancy. The papers examine sex differences in health expectancy indicators in the EU countries, as well as trends in health expectancy in Hong Kong and in the US. They go beyond description of sex differences in health expectancy and assess the contributions of mortality and disability to gender differences in healthy life years and unhealthy life years, investigate temporal changes in sex differential health expectancy, as well as analyze contributions of time and age dimensions to the gender gap. They also show that there is still work to be done to indentify and quantify mechanisms underlying sex differences in longevity, health, and aging.Men die, women suffer: that is what is called the malefemale health paradox (Nathanson 1975;Wingard 1984;Waldron 1995;Case and Paxson 2005;Barford et al. 2006;Oksuzyan et al. 2008). At all ages male death rates are higher than that of females indicating that in terms of mortality women are healthier than men. However, women do worse with regard to disability and other health outcomes (Jagger et al. 2008;Schön and Parker 2008;Christensen et al. 2009;Crimmins et al. 2010). What are recent developments of sex differences in mortality, life expectancy, and health expectancy? Is the gender gap after several decades of increasing trends now decreasing? What are the reasons for these changes?In 1955 Jeff N. Morris showed that in the second half of the nineteenth century in United Kingdom (UK), the death rates were high and increasing among middle-aged individuals (Morris 1955). Men had only about 10% higher death rates than their same-aged female counterparts. Thereafter, due to improved living conditions death rates began to fall from 1900 and continued to decline until the 1920s. From the 1920s, trends in mortality diverged by sexes: improvements in mortality rates stagnated among men, whereas they continued to decline among women. In Communicated by Dorly