The purpose of this study is to describe secular trends in mortality for Sanday, Orkney Islands, Scotland between 1855 and 1974. Using information from death records, standardized crude mortality rates for each 10-year period were decomposed into 12 cause specific mortality rates. Differential contribution of each cause of death to the overall decrease in crude and age specific rates has been determined by comparing rates between periods of highest and lowest mortality. Although the decrease in rates was greater for females than for males, for both sexes, decreased mortality associated with respiratory diseases made the greatest contribution to the overall mortality decline. The decrease in death rates has its greatest effect during the reproductive period. Although results differ from those reported for England and Wales in the nineteenth century, they conform to estimates based on cross-national data from the mid-nineteenth century to the present.