The relationship of Raynaud's phenomenon (RP) to the degree of esophageal motility dysfunction was evaluated in 12 patients with scleroderma. Motility abnormalities of the smooth muscle esophagus were quantitated using a motility index (MI). MI of the scleroderma patients differed significantly from controls. No relationship was noted between the extent of motility abnormality and the duration or severity of the RP. A nearly uniform finding was the absence of coordinated esophageal peristalsis, occurring regardless of the duration or severity of the RP. The study demonstrates that it is not possible to predict the degree of esophageal motility dysfunction in scleroderma based on RP alone. The disease may have two different and independent pathogenetic components. One component is closely linked to RP and involves impairment of neuromuscular electrical transmission. The other component (independent of RP) involves progressive loss of muscle strength in the distal esophagus and in the lower esophageal sphincter.