Inherited thrombophilias are common disorders with a worldwide distribution, including antithrombin, protein C, and protein S deficiencies as well as resistance to activated protein C. Increased understanding of these disorders suggests that thrombophilia can arise from interaction between defective genes and environmental factors. WHO and the international Society on Thrombosis and Haemostasis (ISTH) discussed the problems of inherited thrombophilia at a joint meeting held in Geneva on 6-8 November 1995. The present article reports on the various possibilities for controlling the disorder and makes a series of recommendations for diagnosis, treatment, and research into the condition.