Ruminants lose about 8 to 12 % of their food energy as methane (CH4). Eructation of CH4 from ruminants may contribute to the climatic change and global warming. Reducing CH4 production can be of direct economic benefit because it coincides with greater energy-use efficiency of feeds by the animal. To reduce CH4, antibiotics have been used in addition to their use for growth and disease prevention. However, the European Union has banned the use of antibiotics in animal feeds from January 2006, so there is a need to find alternative methods to reduce CH4 production. It has been shown that tannin and unsaturated fatty acid can play important roles to reduce CH4 production in ruminants (Patra et al., 2006; Giger-Reverdin et al. 2003). Some spices are high in tannin and others are high in fatty acids. In the present study, the chemical composition of five spices and their role in reducing in vitro CH4 production were assessed. Ground wheat (wheat) is a highly fermentable feed as it can produce large amount of gas, and it was therefore used as a substrate to compare the effects of spices on in vitro rumen fermentation in this study.