In order to assess the impact of methane (CH4) production from ruminants on the environment, and to measure the effects of various mitigation strategies for methanogenesis, it is necessary to accurately measure CH4 output under different scenarios. Techniques which enable measurement of CH4 output from individual animals can facilitate a meaningful investigation of factors affecting methanogenesis. Indirect open-circuit respiration calorimetry chambers are an efficient way to measure CH4 production from individual animals. However, chamber measurements cannot be used to measure CH4 output from grazing animals. To overcome this, the sulphur hexafluoride (SF6) tracer technique was developed by Johnson et al. (1994), and is widely used to measure CH4 emissions from individual grazing ruminants. Although the SF6 technique has been used quite extensively, relatively few studies have been carried out to validate its accuracy compared to respiration calorimetry studies. Additional validation studies are required to clarify the situation, especially for dairy cows which are major producers of CH4. Consequently, the objective of this experiment was to use indirect open-circuit respiration calorimetry chambers to validate the SF6 technique for measuring CH4 emissions from dairy cows, and to develop a prediction model for actual CH4 production of dairy cows from SF6 estimates.