The aim of this study was to determine the extent to which variation in socioeconomic factors derived from the 1986 census could "explain" variation in standardised mortality ratio (SMR) between the 322 electoral wards and district electoral divisions (DEDs) in Dublin. Factors examined included percentage of population in the various Irish social class groupings, percentage of male unemployment, number of cars per private household and number of persons per car. Regression analysis between SMR and each of these factors individually showed a significant relationship in every case. The explanatory variables studied were all highly correlated and stepwise forward multiple regression was used to identify factors which had an independent effect. Two factors emerged as significant--percentage of persons in social classes 5 & 6 (semiskilled and unskilled) and number of cars per private household. This model explained 27.4% of the variance in SMR. We conclude that the variation of SMRs between DEDs in Dublin can partly be explained by variation in socioeconomic factors.