It is first reported that plant young proembryos expressed exogenous reporter genes by electroporation. Young proembryos with 8-32 cells and globular proembryos with 250-400 cells could be isolated by enzymatic maceration combined with microdissection. After electroporation with GUS or GFP genes, the proembryos were cultured for 1-2 d in KM8p medium. At the field strength of electroporation 500-1 500 V/cm, blue reaction of GUS or green fluorescence of GFP could be observed in the proembryos. The highest transient expression frequency of young proembryos (2.2%) was obtained at the field strength of 750 V/cm, whereas the highest frequency of globular proembryos (5.9%) was obtained at the field strength of 1 250 V/cm. Taking the proportion of transformed cells in the whole cells of proembryos as efficient transformation frequency, the efficient transformation frequency of the young proembryos was 7 times that of the globular proembryos.