24-hour esophageal multichannel intraluminal impedance (MII)-pH-monitoring is the most accurate method for detecting abnormal gastroesophageal reflux in patients with gastroesophageal reflux disease and other conditions. However, some investigators have found that short-duration conventional pH-monitoring in the postprandial phase is also useful, but it has not been proven for MII-pH-monitoring. Objective: to assess diagnostic capability of 200-minute postprandial MII-pH-monitoring compared to 24-hour study. Materials and Methods. Patients were divided into 2 groups: the 1st(gastroesophageal reflux disease) — 6 women and 9 men, mean age (M ± m) was 44.8 ± 4.2 years; the 2nd (functional dyspepsia) — 6 women and 7 men, mean age was 49.2 ± 3.9 years. We have separately analyzed the data of 200 minutes of the study and the data from the entire 24-hour period. The test period included 45 min before provocative standardized breakfast (507 kcal) and 140 min after. Results. The correlation between the results of both studies was strong: for the number of acid refluxes — r = 0.88 (95% confident interval (CI) 0.76–0.95; p < 0.0001); for the total number of refluxes — r = 0.82 (95% CI 0.64–0.92; p < 0.0001). For the time when pH < 4, the correlation was slightly worse — r = 0.69 (95% CI 0.41–0.85; p < 0.0001). The normal reflux number was calculated by means of ROC-curve. The reflux was considered as abnormal when the number of acid refluxes > 6 episodes for 200 minutes and > 40 for 24-hour period, the total number of refluxes > 17 episodes for 200 minutes and > 74 for 24-hour period. Conclusion. In general, our results indicate that the 200-minute study can be fully utilized to quantify gastroesophageal reflux.