Purpose of the study: to clarify the effect of the concentration of motilin in the blood on the clinical symptoms of functional dyspepsia. Materials and methods. A prospective examination of 90 people aged 22,3±0,17 years was carried out, divided into 3 groups: patients with postprandial distress syndrome (PDS), patients with epigastric pain syndrome (EPS), practically healthy. All subjects were questioned according to the GSRS questionnaire, and the concentration of motilin in their blood was determined before and after the drinking test. Statistical processing included the calculation of mean values, their errors, Student’s t-test, Pearson’s correlation test, factor analysis. Results. In patients with PDS, the intensity of abdominal pain (2,47±0,38 points) does not differ from healthy ones (2,19±0,22 points), in patients with EPS it is higher (4,33±0,51 points). Dyspeptic syndrome is more typical for patients with PDS (2,07±0,12 points) than for EPS (1,10±0,04 points). The concentration of motilin in the blood on an empty stomach with PDS (9605,47±167,64 pg/ml) is higher than with EPS (8780,67±232,27 pg/ml). After the drinking test, the level of motilin in the blood of patients with EPS increased to 9367,33±145,78 pg/ml, the PDS decreased to 9323,33±239,04 pg/ml. With PDS, the severity of reflux syndrome directly correlates with the concentration of motilin in the blood. In EPS, the initial level of motilin correlates inversely with the severity of reflux syndrome, constipation syndrome, and the volume of water drunk. After the drinking test, there is an inverse correlation between the level of motilin and the severity of diarrheal and dyspeptic syndromes, and a direct correlation with the intensity of abdominal pain. The initial level of motilin in the blood brings the greatest factor load into the “factor of motor disorders”. Conclusion. The initial level of motilin and its dynamics during water load play an essential role in the formation of the clinical picture of functional dyspepsia.