There is little information about gastric emptying of extracellular fat. A marker for liquid fat, 99mTc-(V)-thiocyanate, was used to compare gastric emptying and intragastric distribution of oil to that of aqueous liquid and solid meal components. Eight volunteers consumed 60 ml of 99mTc-labeled oil and 290 ml of 113m-In-labeled soup (total 505 kcal) on one day and 280 g 113mIn-minced beef (500 kcal), 60 ml 99mTc-labeled oil and 290 ml nonlabeled soup (505 kcal) on another day. In the oil/soup meal, gastric emptying of oil was slower than soup (50% emptying time 139.1 +/- 16.5 min versus 47.9 +/- 4.5 min, p less than 0.01). There was retention of oil in the proximal stomach (p less than 0.01) and retrograde movement of oil from distal into proximal stomach. In the oil/soup/beef meal, there was no difference in emptying of oil and beef from the total stomach (retention at 180 min 71.4% +/- 3.4% versus 58.3% +/- 7.6%, ns), but more oil was retained in the proximal stomach and more beef was retained in the distal stomach (p less than 0.01). The emptying rate of oil in the oil/soup meal was about twice that for oil consumed in the other meal. There was no difference between the two meals in the number of calories emptied in the first 180 min. These results demonstrate major differences in the intragastric distribution of oil compared to solid and aqueous liquid meals.