Objectives The aim was to assess alcohol-related mortality of persons with mixed and uniform ethnic origins in two national contexts.

Setting Data were from the multigenerational population registers of the total population of Finland and Sweden observed from 1971 to 2017. Study persons were men and women of ethnic Finnish and Swedish background, born in their country of residence.

Participants Persons were born between 1953 and 1999. In Finland, ethnic origin was assessed through own, mother’s and father’s Finnish or Swedish ethnolinguistic affiliation. Data on Sweden included persons born in Sweden, with mother and father born in Sweden or Finland. A total of 2 997 867 and 4 148 794 persons were included in the Finnish and Swedish data, respectively. The total number of alcohol-related deaths by main cause was 13 204 and 3336. Cox regressions were used to examine associations.

Outcome measures For the period 1971–2017, we studied alcohol as the main cause of death. For the period 1996–2017, we observed if alcohol was the main or contributing cause of death. Parallel analyses were performed for all-cause mortality.

Results For men in Finland, the hazard rate of alcohol-related mortality of Swedish speakers with uniform Swedish background was 0.44 (95% CI: 0.38 to 0.52) that of Finnish speakers with uniform Finnish background. The corresponding hazard rate for women was 0.40 (95% CI: 0.28 to 0.55). In Sweden, the hazard rate of men with both parents born in Sweden was 0.40 (95% CI: 0.32 to 0.49) that of men with both parents born in Finland. The corresponding hazard rate for women was 0.50 (95% CI: 0.31 to 0.79). In both countries, persons with mixed background had an alcohol-related mortality rate between that of persons with uniform Finnish and Swedish background.

Conclusion The consistent pattern across countries necessitates increased policy attention towards offspring disadvantaged via parental ethnicity to minimise harmful consequences of alcohol consumption across and within ethnic groups.