During the past 10 years, researchers on both sides of The Sound in the so-called Öresund region have worked together to analyze the causes of the observed differences in life expectancy between Denmark and Sweden. The region includes Copenhagen and North Zealand and the county of Scania in southern Sweden, with Malmö as its largest city. Both Denmark and Sweden held top rankings among OECD-countries in 1970 regarding life expectancy at birth. In 1990 Denmark had fallen to a bottom ranking, while Sweden was still at the top. At a scientific meeting in Malmö on January 26-27, 2000, some 60 presentations were made concerning differences and similarities in health measures on the two sides of the sound which divides the two countries. On the Swedish side, life expectancy is 3-4 years longer than on the Danish side. Paramount among explanations are higher mortality figures due to smoking and alcohol-related diseases on the Danish side, both in men and women (most pronounced). Minor contributions to the differences are suicides and traffic accidents. Historically, Denmark and Sweden have much in common. Until 1658, Scania, the Swedish county to the east of The Sound was part of Denmark. During the past 150 years rather impressive cultural differences have developed. Smoking prevalence and alcohol consumption are more than twice as high on the Danish side of the sound. In coming years, researchers, representatives for the health service systems and others will work together in order to prevent disease and promote health in the Öresund region. The conference was arranged by the Medicon Valley Academy, an EU-supported enterprise seeking to stimulate research and development within the health sector in the Öresund region (also known as Medicon Valley).