Background: We aimed to ascertain the average age at death (AD) in the intellectual disability population for each gender and compare them to those of the general population during 1970-2012. Methods: By analysing medical records, we calculated the ADs of all deceased clients (N = 1236) of two district organizations responsible for intellectual disability services. Statistics Finland's database generated data regarding ADs of all inhabitants who had died after having resided in same district. Results: During the follow-up, average ADs for the intellectual disability population and general population increased, and simultaneously the AD difference between these populations decreased. In the 2000s, the AD difference between the intellectual disability population and the whole population was 22 years for men (95% CI: -24 to -20) and 30 years for women (95% CI: -33 to -27). In 2000s, the mean AD of those with mild-to-moderate intellectual disability (IQ 50-69) for women and men was 56 (SD17) and 54 (SD18), and those with severe to profound intellectual disability (IQ<50), 44 (SD23) and 43 (SD21). Conclusions: Intellectual disability is still a considerable risk factor for early death. Among the intellectual disability population, unlike in general population, the lifespans of women and men are equal.