BACKGROUND: The age at death from different diseases is a good indicator of their relative importance at the population level. METHODS: Use was made of the mortality data provided by the Flemish Community of Belgium on all deaths, WHO ICD-10 coded, for the period 2000-2004. RESULTS: The mean age at death increases with time for nearly all diseases and for both sexes. This increase is highly significant for all-cause mortality. Deaths due to accidents and suicide cause the greatest loss of life expectancy for the individuals concerned. From the disease groups liver cirrhosis, lung and breast cancer have the greatest impact on life expectancy. Women die at higher ages than men for all diseases except lung cancer. They have a highly significantly greater loss of life expectancy due to lung cancer than men. The mean age at death during the period considered increases markedly for breast cancer (p< 0.0001). This suggests an increased efficiency of both treatment and prevention of breast cancer. CONCLUSIONS: Studying the mean age at death from different pathologies is an efficient and rapid way to evaluate the relative importance of different diseases and the changes in the health situation in a given population. Mortality continues to decline in Flanders.