Brief treatment of metaphase II (MII) stage porcine oocytes with 0.4 microg/mL demecolcine in the presence of 0.05 M sucrose produces a membrane protrusion that contains a condensed chromosome mass. The present study examined the optimal conditions for demecolcine and nocodazole treatment in chemically assisted removal of chromosomes. When matured oocytes were treated with 0.1-0.4 microg/mL demecolcine for 60 min or with 0.4 microg/mL demecolcine for 30 min or 3 microg/mL nocodazole for 30 or 60 min, more than 70% of oocytes had a membrane protrusion containing condensed chromosomes were located. There was no difference in the in vitro developmental potential of enucleated oocytes assisted by 0.1 and 0.4 microg/mL demecolcine or 3 microg/mL nocodazole that received porcine somatic cells. After transfer to 10 recipients, however, two of six recipients that received demecolcine-treated enucleated eggs produced four healthy cloned piglets, but none of the four recipients of nocodazole-treated enucleated eggs produced piglets. Further studies are required to increase the successful development to term because the proportion of live piglets was low (4/2, 672, 0.15%).