In this paper, ten concentrated essential oils (juniper, common thyme, pine, peppermint, silver fir, eucalyptus, fennel, tarragon, caraway and wild thyme) were investigated for their antifungal activity against two mould types (Aureobasidium sp. and Alternaria sp.) isolated from masonry. The action of essential oils was investigated using the antibiogram method. Results indicated that the antifungal activity of the essential oils is different. The action of wild thyme, common thyme and fennel essential oil appeared the most interesting, with strong fungicidal effect on both moulds tested, followed by tarragon, caraway and eucalyptus. Pine has different action, depending on the mould type. Peppermint, juniper and silver fir seem to have very small or no inhibitory action on moulds isolated from stone. Some volatile oils induce modifications in moulds pigmentation; in the presence of tarragon and caraway (for one mould type), or thyme and peppermint (for the other mould type), no coloration of the colonies appears.