The aim of the paper is to investigate if inbreeding had any health effects on individuals born 1890–1905 in Skellefteå, Sweden, with a follow-up period until 1950. The effects on longevity, fertility and impairments as outcome variables is of particular interest to clarify, as they provide a comprehensive picture of howinbreeding affects human demographic behaviour and health during this period. The effect on longevity was not strong but caused higher mortality for men above one year of age. The risk of stillbirths showed a substantial association with inbreeding, with a higher risk for highly inbred. The probability of having children was lower for persons representing high levels of inbreeding. However, the number of children given that at leastone child is born is not affected. No significant effect of the parents being related is noted on fertility. With respect to an individual’s own inbreeding we find that the higher the level of inbreeding, the higher the risk of impairments.