The effect of indirect cooling on finger-tip blood flow patterns were recorded in 31 patients suffering from Raynaud's phenomenon. Fifteen were suffering from generalized scleroderma with acrosclerosis (GS), and 16 from primary Raynaud's phenomenon (PR), and were compared to 13 healthy controls without cold sensitivity. Finger blood flow (FBF) was monitored by a laser Doppler flowmeter. Resting blood flow values were significantly lower in patients compared to controls. After two min of body cooling no difference could be observed in relative flow decrease between patients and controls or between PR and GS, but after 10 min of body cooling, relative flow decrease tended to be more pronounced in GS than in PR. Only in GS was the zero flow situation observed. During the resting condition, skin vessel vasomotion was observed as rhythmical variations in the blood flow of 5-10 cycles per minute. These seemed to be preserved in patients and in chronically sympathectomized patients, and could not be abolished by nerve blockade of the finger. The influence from sympathetic vasomotor fibres on FBF could be observed during cooling as irregular coarse flow fluctuations. This was observed in both patients and controls but not in the chronically sympathectomized patients and disappeared after nerve blockade of the finger. Finger temperature was measured simultaneously during body cooling, but significant changes were observed only in normals and PR.(ABSTRACT TRUNCATED AT 250 WORDS)