The prevalence of the prothrombin gene variant (allele 20.210 A), factor V Leiden mutation, and homozygosity for transition 677C→T in the methylenetetrahydrofolate reductase (MTHFR) gene was determined among patients with sickle cell disease (SCD). The group included 73 patients with median age of 32,3 years with a diagnosis of sickle cell anemia in 53 patients, hemoglobinopathy SC in 16 patients, and four with S/β°thalassemia. Vascular complications such as ischemic stroke or deep vein thrombosis were diagnosed in nine patients. Heterozygosity for the prothrombin gene variant or factor V Leiden mutation was identified in four patients. However, only one patient, who developed ischemic stroke, was identified as a carrier of factor V Leiden mutation. None of the patients presented homozygosity for the thermolabile variant of the MTHFR. 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