This study was undertaken to determine whether diploid parthenogenones can assist the development of single blastomeres of 4-cell embryos to term. Isolated blastomeres of 4-cell embryos were aggregated with parthenogenones at the 2-, 4- and 8-cell stages. After the removal of the zonae, aggregation was done by pushing one blastomere of 4-cell embryos and one parthenogenone into contact using a micropipette. There were no significant differences in the percentages of blastocysts and offspring among all parthenogenones' developmental stages used. It also seemed that the chimerism of the offspring (judged by coat color) was not affected by the developmental stage of the parthenogenone. A total of 19 offspring survived and 12 offspring were coat-colored chimera. From 12 coat-colored chimeric offspring, 9 offspring had germlines derived from the isolated blastomeres of 4-cell embryos, one offspring had a germline derived from both the parthenogenone and the isolated blastomere of a 4-cell embryo and one offspring had a germline derived from the parthenogenone. One offspring however, was infertile. The present study demonstrates that parthenogenones can be used to assist the development of single blastomeres from 4-cell embryos to term.