METHODS: Patients with hospital acquired VTE were identified in an academic tertiary care center. 120 cases during January 2015 to February 2016 were randomly selected for analysis for adherence to VTE prophylaxis guidelines. VTE prophylaxis compliance was based on American College of Chest Physicians 9th edition (ACCP) guidelines. Prescription order compliance was defined by appropriate pharmacological and/or mechanical prophylaxis being prescribed for the patient if indicated. Mechanical prophylaxis compliance was defined as appropriate adherence to mechanical prophylaxis during the indicated period. Pharmacological prophylaxis compliance was defined as appropriate dosing being administered during the indicated period. If there was full compliance with the measures, then health care delivery was termed as ‘optimal’ or defect-free. If any hospitalized patients develop VTE despite optimal care, it was classified as potentially non-preventable VTE. If any lapse in adherence to the guidelines was identified, it was termed as ‘sub-optimal’ care. The VTE cases resulting from sub-optimal care were classified as potentially preventable. An algorithm for classification of Hospital Acquired VTEs was developed using the above defined compliance measures.