Blood flow through the brachial and radial artery at different temperatures and during reactive hyperaemia was measured in 23 patients with Raynaud's phenomenon (9 patients with Raynaud's disease, 7 - Raynaud's syndrome with thoracic outlet syndrome (TOS), and 8 - Raynaud's syndrome and scleroderma), and 11 control subjects. Blood flow was determined by an ALVAR pulse-wave Doppler system enabling measurement of vessel diameter and blood flow rate. The measurements suggest that the blood flow through brachial artery reflects the changes of blood flow through the hand immersed in water of different temperatures. Maximum vasoconstriction was the same in all groups of Raynaud's phenomenon. The lowest blood flow at higher temperatures and during reactive hyperaemia was found in patients with scleroderma, whereas in the group of TOS and partly in patients with Raynaud's disease one can suspect only functional changes.