Objective:To describe the vertical clinical pharmacist service's interventions in prevention of venous thromboembolism.Methods:This prospective study was done at a private hospital. From January to May 2012, the clinical pharmacist evaluated medical patients without prophylaxis for thromboembolism. If the patient fulfilled criteria for thromboembolism and did not have contraindications, the clinical pharmacist suggested inclusion of pharmacologic agents and/or mechanical methods for venous thromboembolism prevention. In addition, the appropriate dose, route of administration, duplicity and replacement of the drug were suggested.Results:We evaluated 9,000 hospitalized medical patients and carried out 77 pharmaceutical interventions. A total of 71 cases (92.21%) adhered to treatment so that non-adherence occurred in 6 cases (7.79%). In 25 cases pharmacologic agents were included and in 20 cases mechanical prophylaxis. Dose adjustments, route, frequency, duplicity and replacement made up 32 cases.Conclusion:The vertical clinical pharmacist service included the prophylaxis for venous thromboembolism and promotion of appropriate use of medicines in the hospital.