Antifungal activity of the Thymus bleicherianus Pomel and Thymus capitatus (L.) Hoffm. & Link essential oils againstwood-decay fungi. Essential oils and their constituents have a long history of applications as antimicrobial agents, but theiruse as wood preservatives has rarely been reported. This study deals with the antifungal activity of two medicinal and aromaticplants essential oils of the Moroccan flora against four wood-decay fungi, in order to find new bioactive natural products. Thechemical composition of essential oils extracted by hydrodistillation from the aerial parts of Thymus bleicherianus Pomel andThymus capitatus (L.) Hoffm. & Link was analyzed by GC and GC-MS. The major components of T. bleicherianus oil wereα-terpinene (42.2%) and thymol (23.9%). Carvacrol (70.92%) was the predominant constituent in the essence of T. capitatus.Minimal inhibitory concentrations of the essential oils added to malt agar medium in defined concentrations were determinedby a screening test with the agar dilution method. The oils, object of the survey, showed a strong antifungal activity againstall tested fungi.