Abstract One of the goals of developmental neuroscience in the post-genomic era is to clarify functions of a huge number of anonymous genes of which only DNA sequences are identified. More convenient methods for genetic manipulation in vertebrates, especially mammals, could help us to identify functions of the novel genes. Here we introduce a novel gene transfer technology using electroporation (EP), which is a simple and powerful strategy for genetic analysis. We have applied this method to cultured mammalian embryos in order to understand the function of specific genes in the developing brain. We have also performed EP in developing fetuses in utero guided by ultrasound image. The combination of these techniques in addition to analysis of genetic mutants will clarify functions of individual genes, gene interactions, and the molecular mechanisms underlying the brain development.