To confirm the overcome of in vitro 2-cell block, ICR mouse I-cell embryos were cultured in CZB media. All embryos in CZB were overcome in vitro 2-cell block and 92% of embryos were developed to the blastocyst at day 4. However, in m-KRB group(control) only 20% of embryos were developed over 2-cell. Any embryos in m-KRB did not develop to the morular stage. Developments and degenerations of ICR mouse I-cell embryos were compared in CZB medium prepared with water of three quality:(l) Milli-Q ultrafiltration water(UF);(2) Milli-Q reverse osmosis water(RO);(3) tap water(TAP). The objective was to evaluate the potential of quality control using ICR mouse 1-cell embryos. The more water was purified, the better embryo developments were supported and the less embryos were degenerated. As a quality control system, the culture of ICR 1-cell mouse embryos in CZB was useful.