The importance of the blood coagulation sequence as an integral part in the pathogenesis of diseases inside as well as outside the blood vessels is becoming increasingly apparent. Mononuclear phagocytes have important functions in initiation of coagulation by producing several procoagulant substances, including thromboplastin, the potent trigger of the extrinsic pathway. Increasing evidence demonstrates the clinical importance of monocyte and macrophage thromboplastin synthesis in the pathogenesis of a variety of diseases. This review surveys the role of monocyte/macrophage thromboplastin in relation to inflammatory diseases, cancer, disseminated intravascular coagulation and diseases of the blood vessels, thrombosis and atherosclerosis.