Background: Venous thromboembolism (VTE) is a leading cause of mortality in critically ill patients. Pharmacological thromboembolism prophylaxis is an effective way to prevent thrombosis. Methods: A Padua risk assessment model was used to determine critically ill medical patients’ risk and the appropriateness of pharmacological prophylaxis. Results: Our analysis included 139 patients. VTE prophylaxis was considered appropriate for 89.9% of the patients who received prophylaxis. Non-guideline-approved dosing of heparin was observed in 24.4% of patients. Despite having an indication, 12.8% of patients did not receive prophylaxis. Intravenous prophylaxis was used in 6.6 % of heparin receivers. Thrombosis occurred in 2.6% of all patients. Conclusion: Although most patients received pharmacological VTE prophylaxis, inappropriate dosing of heparin and delays in appropriate pharmacological VTE prophylaxis were common for patients with cerebrovascular disease and tumours. © 2020, Netherlands Society of Intensive Care. All rights reserved.