BACKGROUND/AIMS: Not only scintigraphic measurement of gastric emptying(GE) is not standarized, but also several discrepancies exist in the influence of technical factors including instrument and methods of analysis on gastric emptying studies. The aim of this study was to determine whether investigating instruments, methods of analysis, affect gastric emptying rates of a radiolabeled meal in scintigraphic measurement. METHODS: Using two different scanners (single-headed gammma camera and double headed gammma camera), gastric emptying studies of radiolabeled meal (consisting of 1 g of resin) labeled with 2mCi of 99mTc-DTPA (50g of egg, 150ml of milk, 100g of rice; 611Kcal) were done in 16 healthy volunteers (16 men, age 27.5+/-3yrs). Anterior and posterior image were obtained from the supine position with two scanners at every timing interval. Anterior image only was analyzed to determine whether the differences in instruments affect gastric emptying rates. Sum of anterior and posterior counts obtained by double-headed gamma camera were compared to geometric mean. RESULTS: There were significant difference in gastric emptying rates obtained with anterior image between a single-headed scanner and a dual-headed scanner (P < 0.05, T1/2= 105.8+/-16.3 min vs 80.9+/-14.7 min). Sum of anterior and posterior counts was correlated well with geometric mean (r=0.93). Also observed difference between intraobserver and interobserver variation. CONCLUSIONS: These results indicate that instrumental variations in gastric emptying studies should be considered in interpreting individual study results. The simple sum of anterior and posterior counts could be an useful parameter in the analysis and interpretation of gastric emptying data.