Introduction With the increase of Qatar's total population, primarily due to the influx of healthy male migrant labor, worldwide attention has been focused on deaths among these migrant workers. Objective To describe adult mortality trends in Qataris (nationals) and non-Qataris (migrants) from all causes, cardiovascular and circulatory disease, neoplasms, and injuries, 1989-2015. Methods We retrieved Qatar's vital registration data by nationality, sex, age group, year, and codes of the World Health Organization's International Classification of Diseases, Ninth and Tenth Revisions. We assessed age-standardized mortality rate (ASMR) trends in Qatar's total population, in Qataris and non-Qataris using Joinpoint regression. Findings During the study period, 26,673 deaths were recorded. In 2015, we estimated 60,716 years of life lost (82% in males) in the overall population. In Qataris (both sexes) and in non-Qatari females, all-cause rate decreased significantly and steadily between 1989-2015. In non- Qatari males, it decreased significantly between 1998-2010 probably attributed to a massive influx of healthy migrants. Yearly rates were significantly lower in non-Qataris over 27 years. Reduction in Qatar's total population rates for all causes and for neoplasms can be partially attributed to the healthy migrant effect. For injuries in males, it was lower in non- Qatari. Remarkably, for falls, cause-specific ASMR in non-Qatari males decreased significantly reaching 2.6/100,000 in 2014, suggesting improved safety in the work environment. However, while young adult males in Qatar die predominantly from injuries, young adult females die from neoplasms. Conclusion Our study demonstrates that premature death in young adult males and females in Qatar is predominantly due to injuries and neoplasms respectively. These identified causes of death are for a large part preventable and should be addressed appropriately to lower premature mortality among young adults in Qatar.