Using a combination of environmental and local cooling, we induced vasospastic attacks of Raynaud's phenomenon in nine of 11 patients with idiopathic Raynaud's disease and in eight of 10 patients with scleroderma. Attacks were defined as occurring if two of the possible three color changes (pallor, cyanosis, and rubor) occurred, and serial photographs were scored by three independent raters. Two fingers on one hand were anesthetized by local injection of lidocaine, and the effectiveness of nerve blocks was verified by plethysmography. The frequency of vasospastic attacks in nerve-blocked fingers was not significantly different from that in the corresponding intact fingers on the contralateral hand. These findings show that the vasospastic attacks of Raynaud's disease and phenomenon can occur without the involvement of efferent digital nerves and argue against the etiologic role of sympathetic hyperactivity.