The phylogenetic relationship between the Alectoriaceae and the Parmeliaceae (lichenized ascomycetes) were studied using sequences of the small subunit of the nuclear ribosomal DNA (SSU rDNA). The Alectoriaceae was represented by specimens of Alectoria ochroleuca and A. sarmentosa, and the Parmeliaceae by Bryoria capillaris, Cetraria islandica, Cornicularia normoerica, Evernia prunastri, Hypogymnia physodes, Parmelia saxatilis, Platismatia glauca, Pleurosticta acetabulum, Usnea florida, Vulpicida juniperina, V. pinastri and Xanthoparmelia conspersa. The results suggest that the Alectoriaceae is derived from within the Parmeliaceae, and it is suggested the families should be treated as synonyms. Morphological and anatomical characters are discussed, and it is concluded that earlier investigations might have overemphasized minor variations in ascus structure.