Methane production in sheep is a novel trait that requires the development of consistent measurement protocols. The objective of this study was to estimate repeatabilities for methane production adjusted for liveweight measured in portable accumulation chambers in Merino ewes on pasture. Repeatabilities were low to moderate. No improvements in accuracy of the phenotypic variance could be achieved by additional measurements. Most likely the trait expressed at different ages and in particular different physiological status was not the same in lactating and dry animals, but prove of this hypothesis was outside the scope of the analysis in this study.