There are few powerful techniques available to transfect insect tissues. We previously used biolistics to transfect Bombyx mori embryos, and larval and pupal tissues (Thomas J-L et al. 2001. Journal of Insect Science 1/9, Kravariti L et al. 2001. Insect Biochemistry and Molecular Biology 31: 473-479). As the main limitation was the irregularity in results we explored electroporation as an alternative technique by adapting techniques used for chicken embryos to B. mori embryos. By injecting the DNA solution into the hemocoel of late embryos that were finishing organogenesis, we expressed marker genes in numerous tissues following electroporation. With some adaptation of the method this was also achieved for early embryos lacking a hemocoel. Some larval tissues were also transfected. During these technical studies we found that optimizing parameters such as electrical voltage, number of pulses and their frequency, and conductivity of the buffer was important. These results confirmed that electroporation is a reliable technique for transfecting B. mori tissues.