Thrombophilia, which describes a series of conditions in which there is an increased tendency to form clots, is one of the causes of recurrent pregnancy loss.Pregnancy in itself constitutes a hypercoagulability state. Pregnant women that are thrombophilia carriers are more susceptible to develop thrombosis.Thrombophilia may be hereditary or acquired. The hereditary thrombophilias have been increasing in the last few years, and include mutations of factor V Leiden, prothrombin, and the gene that codes the enzyme methylene tetrahydrofolate reductase, as well as the natural anticoagulant deficiencies (antithrombin III, protein C, and protein S), the dysfibrogenaemias, and homocystinuria. Among the acquired thrombophilias are found, anti-phospholipid syndrome, activated protein C resistance with no alterations in the Factor V gene, and mild or moderate hyperhomocysteinuria.