Aim.  Elucidation of the possible risk factors of venous oedema in the patients presenting with primary varicose veins of the lower extremities. Material and methods. The search for the possible risk factors of venous oedema was undertaken in the patients presenting with primary varicose veins of the lower extremities whose illness followed the natural course unaffected by the extraneous factors, i.e. in the absence of treatment. The study included 189 patients with C2 (n=136) and C3 (n=53) primary varicose vein disease who were listed in the database of the SPECTRUM project. These patients either had never before applied for the medical assistance or had failed to compile with the medical prescriptions. The intellectual data analysis and the logistic regression method were used to treat the data obtained in the study. Results and discussion. The logistic regression analysis revealed four factors influencing the probability of the development of venous oedema, viz.  BMI (odds ratio: 1.11, 95% CI: 1.03—1.19), working in the standing or sitting positions during more than previous 5 years or longer period (odds ratio: 4.8, 95% CI: 2.05—12.18), the  duration of the disease of less than 5 years (odds ratio: 0.33, 95% CI: 0.12—0.86), and primary varicose veins in the patient’s parents (odds ratio: 0.44, 95% CI: 0.20—0.96). In other words, the risk factors of venous oedema include long-term practicing a profession in the orthostatic position and  elevated BMI.  «The protective factors» are the duration of the disease of less than 5 years and hereditary background (the risk of venous oedema is lower in the patients whose parents suffered from varicose vein disease). The intellectual data analysis showed that the maximum influence is exerted by the body mass, duration of the disease, BMI, working in the standing or sitting positions during at least 5 previous years , the height, and hereditary predisposition. The patients weighing over 95 kg had OR  3.2 (95% CI: 2.2—4.7). Those with BMI more than 20.45,weighing less than 95 kg and being ill over one year had a higher risk of  developing C3 primary varicose veins if they worked in the standing and sitting positions during at least 5 previous years (OR 2.9, 95% CI: 1.4—6.1). In the patients less than 163 cm in height, with BMI over 20.45 weighing less than 95 kg and being ill during more than 4 previous years, OR  was 1.6 (95% CI: 1.0—2.7). The family history proved to be a protective factor in the case of both building up the decision tree and using logistic regression analysis. All other conditions being equal, hereditary predisposition (primary varicose veins in the patient’s parents) reduces the risk of the development of venous oedema by 50% (OR 0.5; 95% CI: 0.24—1.5). Conclusion. The risk factors for the development of venous oedema in the patients presenting with primary varicose veins include the body mass, long-term practicing a profession in the orthostatic position and  the duration of the disease. The putative protective factor reducing the probability of venous oedema is hereditary background.