The gastric emptying function tests were carried out in eight patients with pancreatic diabetes, who were classified into two groups according to the coefficient of variation in the R-R interval in ECG (C.V. R-R) on the normal subjects: < or = the mean - 2SD (the autonomic nerve dysfunction group: AND+ group) and > the mean - 2SD (the autonomic nerve normal group: AND- group). Both the gastric emptying of liquid food by the acetaminophen method and that of solid food by the isotope method were significantly reduced in the AND+ group than in the AND- and normal groups. In addition, a significant correlation was found between the C.V. R-R and the serum acetaminophen concentration (a 45 min value) and the % gastric retention of isotope (a 120 min value). The above results demonstrated that even pancreatic diabetes might be complicated by gastroparesis diabeticorum among autonomic nerve dysfunction. There was a close relation of delayed gastric emptying to the C.V. R-R in ECG or an index of the vagus nerve function.