Mammalian, including human, spermatozoa undergo morphological and physiological changes during sperm maturation. There were, these changes may affect the fertilization and embryonic development. In this study, we examined the pronucleus formation, pronucleus disappearance and embryonic development in the human oocytes fertilized by intracytoplasmic sperm injection (ICSI). The injected spermatozoa were grouped into ejaculated, epididymal and testicular by the collecting region. Among 363 metaphase II injected oocytes, 287(79.1%) oocytes were normally fertilized and displayed two pronuclei. There were no difference in the fertilization rates and in the pronucleus formation and pronucleus disappearance at 16, 20 and 24 hr after ICSI, among the each spermatozoa group. Also, at 64 hr, the appearance of embryonic development was similar. From these results it can be concluded that there was no difference of maturity among the sperm collected from ejaculated, epididymis and testis in the pronucleus formation and embryonic development. Therefore, testicular spermatozoa are successfully used with ICSI in IVF-ET program.