Many patients with severe idiopathic constipation complain of upper gastrointestinal symptoms, and these often persist after subtotal colectomy. To determine if there is a disturbance of upper gastrointestinal motility in this condition, we have studied gastric emptying for solids (111In-containing pancake) and liquids (99mTc-containing orange juice) for a longer period after a meal (6 hr) than in previously reported gastric emptying studies. Small bowel transit for solids was also measured. All patients had emptied their colon the day before the study. Twelve women (mean age 36 years) with a bowel frequency of less than once per week, proven slow intestinal transit, and a normal diameter colon were studied. Twelve healthy controls (eight female and four male, mean age 33) were also studied. As a group the constipated patients demonstrated no statistically significant delay in emptying during the first 3 hr, although the emptying rate for three of 12 individuals fell outside the normal range. However, at 6 hr after ingestion of the meal, six of 10 patients had residual gastric contents greater than normal--up to 48% solid residue (median: 11% for patients and 0% for controls, P < 0.01) and 40% of liquid (median 9% vs 0%, P < 0.01). Three of four patients with upper gastrointestinal symptoms 6 hr after the meal had gastric retention of solids markedly outside the normal range (48%, 32%, and 16%; normal < 4%). Small bowel transit time was assessed as the time for the solid phase to pass from the duodenum to the cecum; the constipated patients demonstrated delayed transit (median: 75 vs 55 min, P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)