Hemophilia-like disease may be defined as a hemorrhagic diathesis characterized by a prolonged clotting time and the presence of a circulating anticoagulant. Clinical data, such as occurrence in females or onset late in life in males, are of great value in establishing the diagnosis. It is to be distinguished from hemophilia complicated by the development of an anticoagulant following blood transfusions. Differentiation of these disorders is of practical significance because hemophilia-like disease is not hereditary and the clotting anomaly may disappear spontaneously.

2. Two cases with circulating anticoagulants are reported. In the first patient with hemophilia-like disease the anticoagulant was dialyzable and present for a limited period of time only. In the second patient, a 4 year old boy, the distinction between hemophilia-like disease due to an anticoagulant and pre-existing hemophilia with a complicating anticoagulant could not be made.

3. Analysis of the mode of action of the anticoagulants in these 2 cases showed interference with the formation of thromboplastin, although some antithromboplastic activity could not be excluded.

4. A simple technic for testing for circulating anticoagulants is described. It is recommended that this test be performed routinely in all patients with a bleeding tendency and a prolonged clotting time.

ACKNOWLEDGMENTS We are indebted to Dr. Raphael Isaacs for permission to study his private patient. We gratefully acknowledge the assistance of Miss Helen MacLean from the Department of Bacteriology in performing the precipitin tests.