OBJECTIVES: In an effort to improve the prevention of venous thromboembolism, the Nancy University Hospitals conducted a survey of medical practice concerning indications for preventive therapy and surveillance of platelet counts and anti Xa activity. METHODS: The survey involved 163 medical files. Questionnaires were filled out in 6 units (3 medical wards and 3 intensive care units). RESULTS: indications for preventive therapy were found to be quite variable with the exception of very low risk of thromboembolism where the treat/do not treat ratio was 0.1/1, indicating a clear tendency for abstention. This ratio was 0.77/1 and 0.38/1 respectively for low and moderate risk and 2/1 for high risk There was undoubtely a ward effect. The attitudes in practice tended toward non-prevention in patients without limited mobility. For platelet counts, an initial count was performed in 95% of the cases and during treatment in 38% although the specific rates were not the same for different types of units. Anti-Xa activity, which according to prevention recommendations need not to be determined, was not monitored in 88% of the cases. in accordance with prevention recommendations, anti-Xa activity was not determined in 88% of the cases. CONCLUSION: Further progress is needed in the prevention of venous thromboembolism and should be based on wider use of existing methods. (C) 1998, Masson, Paris.