The hospitalized patients of the psychiatric wards represent a risk group for the development of venous thromboembolism. Apart from sedative administration, total movement reduction, bad life style and daily routine and increased body weight, there is negative impact of dehydration, prolonged hospitalization and sometimes immobilisation in consequence of mechanical restraints. A large amount of patients are treated with antipsychotics that have a series of adverse effects. Depending of the drug used, the most frequent of them are somnolence, fatigue, extrapyramidal syndrome, hypotension, hepatotoxicity, increased body weight, prolongation of the QT interval of the ECG with a risk of ventricular arrhythmias, hematopoietic disorders, lipid or glycide metabolism disorders or hyperprolactinemia. Another potential adverse effect of these drugs is the heightened risk of venous thromboembolism development (deep vein thrombosis and/or pulmonary embolism). There is the risk of a pathological blood clotting event in psychiatric patients, especially those treated with antipsychotics. Although it is not high, it can have fatal consequences when combined with a relatively frequent pulmonary embolism and difficult diagnostics of thromboembolism. An algorithm for thromboembolism prevention has been developed. It involves important general risk factors of venous thrombosis (VTE history, immobilisation, malignancy, age over 75 years etc.) and also markers (physical restraints, dehydration, obesity, antipsychotics use) that can participate in the pathogenesis of venous thrombosis in the hospitalized psychiatric patients with limited motility. The authors believe that this prophylaxis is indicated, safe, effective and that it improves the quality of life at relatively low costs.