The COVID-19 pandemic has underscored the vital importance of healthcare systems, particularly intensive care units (ICUs), which serve as critical care environments for severely ill patients. Due to the complex and high-risk nature of their conditions, ICU patients face some of the highest mortality rates in hospitals. While research shows that women generally have longer lifespans than men, it remains uncertain whether this trend holds true for critically ill patients. Additionally, the impact of age on mortality rates — specifically, whether older patients are more likely to die than their younger counterparts — requires further investigation. This research aims to explore these questions. This study stands out by utilizing a vast database of more than 10 000 patients across over 1 000 ICUs — a significant advantage, as many ICU studies are limited by smaller patient cohorts. The findings indicate that sex does not significantly impact the risk of mortality in ICU patients. However, there is a pronounced increase in mortality associated with advancing age. Specifically, patients aged 80 and older face nearly four times the risk of death compared to those aged 18-39, even when accounting for the severity of their conditions. This suggests that among two patients with identical illness severity — one aged 18 and the other 85 —the older patient has a fourfold higher likelihood of dying. Additionally, an intriguing observation emerged within the 60-69 age group: women in this category did not experience the same stepwise increase in mortality as their male counterparts. This finding highlights the need for further investigation. Relevance The study Mortality in ICU patients Stratified by Sex and Age Categories provides valuable insights into mortality trends among intensive care unit patients. It reveals no significant mortality difference between male and female patients — contrasting with the general life expectancy trends, favoring females — and demonstrates a clear, age-related stepwise increase in mortality. Notably, women aged 60-69 deviate from this pattern, lacking the expected rise in mortality. This research deepens our understanding of age- and sex-related mortality differences in ICU settings, offering evidence that can inform clinical decision making. By equipping healthcare providers with more precise mortality risk data, these findings support targeted treatment approaches, optimize resource allocation, and enhance patient outcomes. Given the aging population, the study’s insights hold particular societal relevance, underscoring its importance for current and future healthcare planning.