Objectives: Characterise the circumstances associated with death during admission of adults with Down syndrome (DS) and to identify predictors of mortality. Patients and Methods: Observational study based on data on all emergent admissions of adults with DS to hospitals of the Spanish National Health System between 1997 and 2014. We analysed epidemiological and clinical variables. Results: We analysed admissions of 11,594 adults with DS, mean age 47 years. 1715 patients died (15%), being the highest mortality (35%) in individuals aged 50-59. A past medical history of cerebrovascular disease (aOR 2.95 [2.30-3.77]) or cancer (aOR 2.79 [2.07-3.75]), gross aspiration's admission (aOR 2.59 [2.20-3.04]), immobility (aOR 2.31 [1.46-3-62]), and readmission within 30 days (aOR 2.43 [2.06-2.86]) were identified as predictors of mortality. Conclusions: Adults with DS have a high in-hospital mortality rate. The main predictors of death were cerebrovascular disease, cancer, early readmission, and conditions commonly associated with advanced dementia.