Hereditary thrombophilia was detected in 18 patients (8.33 %) – FVL mutation (heterozygote) in 11 patients (5.12 %), Factor II 20210G > A mutation (heterozygote) in 6 patients (2.80 %) and, in one patient, both mutations (FVL and F II 20210G > A heterozygote) were proved. The gene discussed is F5; the disease is thrombophilia.