This experiment was carried out to investigate the effects of some factors, such as maturation rates according to the culture media, collecting times from slaughter to initiation of incubation and with or without cumulus cells, on in vitro maturation of oocytes collected from follicles (3-5mm diameter) of the gilts slaughtered at a local abattoir. The results obtained were summarized as follows: 1. Two-thousand and eight oocytes were classified as [Good], [Fair] and [Poor] by morphological integrity, and those were 23.2%, 60.0% and 14.7% of the total oocytes collected, respectively, and 42(2.1%) oocytes were degenerated. 2. When oocytes obtained either lhr. or 2hrs. after the slaughter of the donors were cultured for 20hrs., 30hrs. and 40hrs. in m-KRB solution, the maturation rates were 0%, 31.3% and 58.8%, or 0%, 17.5% and 39.7%, respectively. The degenerative oocytes were increased in accordance with hours of cultivation. 3. When follicular oocytes were recovered, most of them were in GV stage, 45.3% of the oocytes reached Met-I after 20hrs. in culture, 73.1% of the oocytes reached Met-Ⅱ after 40hrs. in culture and futher incubation could not increase the proportion that matured. 4. After in vitro culture of follicular oocytes in TC 199, Ham`s F-10 and m-KRB, the proportions of the oocytes matured to Met-II stage were 75.0%, 72.3% and 73.1% respectively. 5. The maturation rates were 73.5% and 24% after 40 hours cultivation in the oocytes with intact cumulus cells and without cumulus cells, respectively.