Objective. To perform an in-depth prospective analysis of the prevalence, risk factors, specific characteristics of venous thromboembolism (VTE) and the dynamics of venous thrombosis during the treatment with low-molecular-weight heparin (LMWH) in patients with different forms and severity of Guillain—Barre syndrome (GBS) admitted to an intensive care unit (ICU). Material and methods. Prevalence, risk factors and course of VTE were analyzed for the first time in 65 ICU inpatients with various forms and severity of GBS. Neurological status was evaluated at baseline and in dynamics, duplex scanning of veins of the legsin the system of inferior vena cava was performed. Results and conclusion. Despite the preventive using of LMWH, a half of patients with GBS, regardless of the form of the disease during the progression of neurological symptoms, have VTE (deep vein thrombosis—52%, pulmonary embolism — 15%). Significant risk factors include: severe disease course requiring artificial ventilation, bed rest for more than 3 days, infectious complications, the presence of the catheter in the central vein, age over 40 years. Venous thrombosis in the system of inferior vena cava in patients with GBS does not differ from that in other critical illnesses suggesting that this pathological process is universal. Preventive measures for this category of patients is insufficient and requires a search for other prevention strategies.