Ruminants produce the methane (CH4) in large quantities. Its eructation led to both energy losses for animals and a worsening of the greenhouse by its radioactive power. The aim of this study was to investigate the influence of essential oils (EO) extracted from Pituranthos scoparius on the methane production and the rumen digestibility. The extraction of EO wasmade by steamdistillation. Pituranthos scoparius essential oils (PS-EO) was investigated for its oil content using the ordinary Gas chromatographyÂmass spectrometry (GC/MS) analysis. The effect of these EO on the methane production, the digestibility of the dray and organic matter and the protozoa counting was studied in in vitro gas production test, using 200mg of vetch-oat hay in a 60ml graduated syringes. EO are added at three doses: 50, 100 and 200 ìl. Total gas and methane production were recorded at 2, 4, 6, 8, 24, 48 and 72h of incubation. GC-MS analysis allowed for the identiûcation of 32 compounds as main constituents. The major constituents were myristicin (12.1 %), 7-methoxy- 3-methyl-1H-isochromen-1-one (10.6%) 1-cyclohexyliden-2-methylpropene (9.9%), Limonene (8.5%), p-Cymene (5.2%) and Thymol (4.8%).The results of this study indicate that EO decreased the methane production after 72 hours of fermentation for the different doses. This decrease the number of protozoa on which the methanogenic archaea was grafted. The results of the digestibility showed that EO deteriorate the digestibility of the dray and organic matter of the oaten vetch hay. The results indicate that the PSEO had a potential to reduce methanogenesis in the rumen, but further in vitro and in vivo trials are required to search optimum dose which reduce methane production without adversely changing dietary fermentation and rumen function.