Gastric and esophageal emptying were assessed using scintigraphic techniques in 13 patients with polymyositis or dermatomyositis and in 13 normal volunteers. Esophageal emptying was significantly delayed in patients, with 8 of 13 patients being outside the normal range. Gastric emptying was also markedly slower in patients than in controls, with 8 patients being outside the normal range for solid emptying and 8 patients beyond the normal range for liquid emptying. The 5 patients with dysphagia all had delayed esophageal emptying, but both gastric and esophageal emptying were delayed in some asymptomatic patients. There was a significant correlation between esophageal emptying and both solid and liquid gastric emptying in the patients. Both gastric and esophageal emptying correlated with the severity of the peripheral (skeletal) muscle weakness. These results indicate that profoundly delayed gastric and esophageal emptying are common in polymyositis and dermatomyositis, implying frequent malfunction of the smooth muscle of the upper gastrointestinal tract in this disease.