The UK is bound by the UN Framework Convention on climate change to reduce methane emissions to below 1990 levels by the year 2000. The Kyoto protocol requires a further cut of 12.5% by 2010. Ruminants are estimated to produce 74 Tg of methane per year (Benchar et al. 1998) which represents about 15% of total emissions (Crutzen et al., 1986). Therefore any reduction in the release of methane gas by enteric fermentation from the dairy herd is environmentally important. The objective of this study was to use data obtained from calorimetry trials to generate multiple regression equations predicting the levels and variability of methane emissions from dairy cows.