In this study, we investigated the effect of adding glucose to in vitro maturation (IVM) medium on the nuclear maturation and ATP metabolism of cumulus cell-enclosed porcine oocytes (COs). When various concentrations of glucose (0.00, 2.78, 5.55, 11.10 and 16.65 mM) were added to IVM medium, the nuclear maturation rate up to the metaphase stage of the second meiotic division (M-II stage) in the 2.78 mM group (67.90%) was significantly higher than that of the non-glucose (0.00 mM, 31.66%) group (p<0.05). In addition, when cumulus cell-denuded oocytes (DOs) were matured in medium with or without 2.78 mM glucose, the rate of DOs maturing to the M-II stage with glucose (53.17%) was significantly higher (p<0.05) than that in the group in which glucose was not added (23.53%). However, these values for DOs were significantly lower (p<0.05) than those for COs (with glucose:71.85% and without glucose: 38.10%). Conversely, the ATP content of COs and DOs matured with glucose were almost the same as those matured without glucose. These results indicate that glucose may stimulate nuclear maturation without changing ATP metabolism.