The mortality of men aged 15-64 who were seeking work in the week before the 1971 census was investigated by means of the OPCS Longitudinal Study, which follows up a 1% sample of the population of England and Wales. In contrast to the current position, only 4% of men of working age in 1971 fell into this category. The mortality of these unemployed men in the period 1971-81 was higher (standardised mortality ratio 136) than would be expected from death rates in all men in the Longitudinal Study. The socioeconomic distribution of the unemployed accounts for some of the raised mortality, but, after allowance for this, a 20-30% excess remains; this excess was apparent both in 1971-75 and in 1976-81. The data offer only limited support for the suggestion that some of this excess resulted from men becoming unemployed because of their ill-health; the trend in overall mortality over time and the pattern by cause of death were not those usually associated with ill-health selection. Previous studies have suggested that stress accompanying unemployment could be associated with raised suicide rates, as were again found here. Moreover, the mortality of women whose husbands were unemployed was higher than that of all married women (standardised mortality ratio 120), and this excess also persisted after allowance for their socioeconomic distribution. The results support findings by others that unemployment is associated with adverse effects on health.