ObjectiveTo describe and characterize a cohort of octogenarian patients admitted to the ICU of the University Central Hospital of Asturias (HUCA). DesignRetrospective, observational and descriptive study of 14 months’ duration. SettingCardiac and Medical Intensive Care Units (ICU) of the HUCA (Oviedo). ParticipantsPatients over 80 years old who were admitted to the ICU for more than 24hours. InterventionsNone. Main variables of interestAge, sex, comorbidity, functional dependence, treatment, complications, evolution, mortality. ResultsThe most frequent reasons for admission were cardiac surgery and pneumonia. The average admission stay was significantly longer in patients under 85 years of age (p=0,037). 84,3% of the latter benefited from invasive mechanical ventilation compared to 46,2% of older patients (p=<0,001). Patients over 85 years of age presented greater fragility. Admission for cardiac surgery was associated with a lower risk of mortality (HR=0,18; 95% CI (0,062-0,527; p=0,002). ConclusionsThe results have shown an association between the reason for admission to the ICU and the risk of mortality in octogenarian patients. Cardiac surgery was associated with a better prognosis compared to medical pathology, where pneumonia was associated with a higher risk of mortality. Furthermore, a significant positive association was observed between age and frailty.