Backgroud/Aims: The aim of this study was to identify gastric contraction by surface electrogastrography (EGG). METHODS: Ten functional dyspeptic patients were included. Antropyloroduodenal manometry and EGG for functional dyspeptic patients were simultaneously recorded during two hours of the fasting peroid. For EGG signal acquisition, the high cutoff frequency was set on 8 Hz and the signal sampling frequency was 16 Hz. For EGG signal analysis, fast Fourier transformation of running spectral analysis was used. RESULTS: During motor quiescence period, the EGG showed normal smooth sine wave, and on time domain frequency analysis, there was a single dominant wave of three cycles per minute (3 cpm). During gastric contraction, the slow wave increased in its amplitude and changed its configuration into a late peak on its wave form. On time domain frequency analysis, there was also dominant frequency of 3 cpm, and a marked increment in the first harmonic during the contraction compared with the motor quiescence period. There were rough correlations between the power of the first harmonic and the gastric contractions. CONCLUSIONS: Gastric contractions could be assessed by changes in waveform and power of first harmonic in addition to change in amplitude on surface EGG.