The aim of our study was to evaluate in 18 diabetic patients (11 with and 7 without evidence of autonomic neuropathy as revealed by common cardiovascular tests) alterations indicative of autonomic nervous involvement of the gastrointestinal tract, independently of the presence of suggestive symptoms. All patients, without evidence of obstructive or mucosal pathology of the upper gastrointestinal tract, underwent the following: 1) study of gastric emptying time of nonabsorbable radiopaque markers (90, 120, 150 and 210 min); 2) study of gastric acid secretion: basal (BAO) and peak (PAO) acid output after sham-feeding (PAOSF) and peak acid output after pentagastrin (PAOPENT).PAOSF/PAOPENT ratio is an index of vagal integrity; 3) esophageal manometry. Our data confirm that a delayed gastric emptying of undigestible solids is a frequent finding in diabetic subjects. This was highly significant (p less than 0.01) at 150 min after a standard meal, in patients with signs of autonomic neuropathy and was often associated with asymptomatic esophageal motor abnormalities. No correlation was found with index of vagal integrity, hormonal pattern and degree of glycemic control. Autonomic neuropathy cannot be considered the only explanation for gastric and esophageal abnormalities in decompensated diabetes.