This study was conducted to investigate the effect of prostaglandin E₂(PGE₂) and indomethacin upon the electrical activity of the isolated cat stomach muscle strips(1.5 X 7.0 cm). Fifty-seven muscle strips, obtained from 57 cat stomachs(including corpus and antrum) were studied in a muscle chamber filled with Krebs solution(pH 7.4, temperature 36±0.5℃) aerated with 5% CO₂ in O₂. The electrical activity was recorded by five capillary electrodes (Ag-AgCl), of which two were placed on the corpus and three on the antrum. After recording of the electrical activity in normal Krebs solution, PGE₂ in concentrations of 0.25(N=7), 0.5(=7), 1(N=7) and 2 X 10^-7 M(N=6) were administered to 27 muscle strips, while indomethacin was applied in concentretions of 0.25(N=9), 0.5(N=10), 1(N=6) and 2 X 10^-3 M(N=5) to the remaining 30 strips. The mean frequency were minutely measured from each electrogastrogram. 1) By adding PGE₂ in all doses, gastric slow wave frequency increased significantly compared with that in resting state. 2) Following PGE₂ administration, peak slow wave frequency increased dose-dependently. 3) After indomethacin addition in all doses, the slow wave frequency decreased significantly compared with that in resting state. 4) Following indomethacin administration, incidence of complete abolition of slow wave increased dose-dependently, and its latent period decreased also in a dose-dependent manner. It is inferred from the above results that prostaglandin E₂ has a facilitatory role in the development of gastric slow wave in cat.