The value of measuring gastric emptying time by ultrasonography in disorders of gastric motility was first assessed in a control group (26 men, 24 women; mean age 51 [23-83] years. Some were healthy volunteers, others were patients without any gastrointestinal disease, the results serving to standardize the method (planimetry of the antrum; 300 mi water as test substance). The mean gastric emptying time (GET) was 24.9 +/- 4.7 min. After this the method was applied in 48 patients (29 men, 19 women; mean age 57.5 [15-90] years) with diabetes type I (n = 14) or II (n = 34) and 59 patients (18 men and 41 women; mean age 54.8 [26-74] years) with functional dyspepsia. GET was 35.9 +/- 12.7 in the diabetics, significantly longer than normal (P ( 0.0001). 24 diabetics (50%) had a prolonged GET (greater than or equal to 40 min) independent of type, duration and treatment of-the diabetes, but more common if the blood sugar level was poorly controlled and there was late diabetic neuropathy. GET was also significantly prolonged in patients with functional dyspepsia (31.4 +/- 9.7 min; P < 0.055). There was a positive correlation with the clinical dysmobility type of the dyspepsia. - It is concluded from the findings that ultrasonographic measurement of GET successfully identifies noninvasively abnormal gastric motility in different types of disease.