Foreign genes were successfully introduced into the fertilized eggs of fish via electroporation, and transgenic fishes integrated with foreign gene were obtained. The transfer efficience (TE) was up to 62.5% in the optimum condition, well compares with the results of microinjection method of gene transfer. The toleration of the fish fertilized eggs against electroporation was tested using a capacitor-based electroporator. The embryogenesis of loach and gold fish were not hindered by electroporation when it's voltage was set at 250V and it's width (duration) were below 6.6ms and 2.4ms respectively. Dot blot analysis of embryonic DNA showed that the replication of the foreign gene (pMhGH) in host loach eggs was accelerated from blastula stage to gastrula stage, then decelerated. Both total DNA of 1-month-old loach and 3-month-old gold fish were dot blotted to detect the persistence of foreign gene. The TE and the persisted copy number (PCN) were positively correlated with voltage, width and electric quantity of pulse, and negatively with the lag between fertilization and electroporation. There were not significant difference between the TE and PCN of circular pMhGH and linear pMhGH/H when transferred into eggs of gold fish. The integration of the introduced linear pMhGH/H not circular pMhGH, was surely demonstrated by the restriction enzyme digestion followed by Southern blot of total DNA extracted from transgenic gold fish.