A LTHOUGH many hundreds of papers have been written on Raynaud's disease, there is still no clearcut clinical concept of the mechanism involved nor an explanation for the varied pictures which are all classified under the term. The problem has been further complicated by the introduction of the term "Raynaud's phenomenon," since there is no agreement as to just what differentiates Raynaud's disease from Raynaud's phenomenon. The modern concept of Raynaud's disease which has been generally accepted is that the attack of dead whiteness in the fingers or cyanosis is due to a local fault in digital or palmar arteries, so that they constrict abnormally to cold and with nervous tension. Certain observations that we have made led us to doubt that arterial spasm can explain the entire picture of Raynaud's disease. These observations have enabled us to separate patients with the syndrome into several groups on the basis of