AIM: The aim of this paper was to assess the prevalence of concurrent deep vein thrombosis (DVT) and/or pulmonary embolism (PE) in the patients with superficial vein thrombosis (SVT) of the legs and to find factors significantly and independently associated with coincident DVT/PE. METHODS: In the setting of a tertiary referral hospital, patients with SVT, attending vascular clinic, underwent physical examination, laboratory testing and leg vein ultrasound (in the case of clinically suspected PE also perfusion/ventilation lung scan or/and helical CT pulmonary angiography). In statistical analysis, we used unpaired t-test, non-parametric Wilcoxon rank sum test, stepwise logistic regression and multivariable logistic regression model. RESULTS: We examined 138 patients (age 61.4 ± 13.9 years, 36.2% men), with ST mostly on varicose veins (89.9%). The prevalence of concurrent DVT/PE was 34.1%. Neither the clinical manifestation nor SVT localization differed significantly between the group with isolated SVT and that with coincident DVT/PE. Of all the assessed patients characteristics (age and sex, BMI, history of SVT, DVT or PE, hypercoagulable states, cardiovascular risk factors) only two factors were significantly and independently associated with the presence of concurrent DVT/PE. Log BMI was significantly higher in the patients with isolated SVT. Factor V Leiden (FVL) was proved as an independent risk factor for concomitant DVT/PE with odds ratio 2,531 (95% CI 1,064-6,016). CONCLUSION: The prevalence of concurrent DVT/PE in patients with SVT, referred to hospital vascular clinic was 34.1%. Lower BMI (log BMI, respectively) and the presence of FVL were significantly and independently associated with concurrent DVT/PE. Our results should be further investigated in a larger prospective study.