Purpose: Left ventricular (LV) diastolic dysfunction is important in critically ill patients, but prevalence and impact on mortality is not well studied. We classified intensive care patients with normal left ventricular function according to current diastolic guidelines and explored associations with mortality., Material and Methods: Echocardiography was performed within 24 h of intensive care admission. Patients with reduced LV ejection fraction, regional wall motion abnormality, or a history of cardiac disease were excluded. Patients were classified according to the 2016 EACVI guidelines, Recommendations for the Evaluation of LV Diastolic Function by Echocardiography., Results: Out of 218 patients, 162 (74%) had normal diastolic function, 21 (10%) had diastolic dysfunction, and 35 (17%) had indeterminate diastolic function. Diastolic dysfunction were more common in female patients, older patients and associated with sepsis, respiratory and cardiovascular comorbidity as well as higher SAPS Score. In a risk-adjusted logistic regression model, patients with indeterminate diastolic dysfunction (OR 4.3 [1.6-11.4], p = 0.004) or diastolic dysfunction (OR 5.1 [1.6-16.5], p = 0.006) had an increased risk of death at 90 days compared to patients with normal diastolic function., Conclusion: Isolated diastolic dysfunction, assessed by a multi-parameter approach, is common in critically ill patients and is associated with mortality., Trial Registration: Secondary analysis of data from a single-center prospective observational study focused on systolic dysfunction in intensive care unit patients (Clinical Trials ID: NCT03787810., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)