A study of the Cladoniaceae has been carried out in Bulgaria, based on new collections from 61 different localities. Thirty five species were found (34 Cladonia and 1 Pycnothelia species), seven of which are new records to Bulgaria, Cladonia asahinae, C. conista, C. cyathomorpha, C. diversa, C. magyarica, C. novochlorophaea and C. peziziformis. As a result of this study the total number of Bulgarian Cladoniaceae species rises to 55, belonging to two genera, Cladonia and Pycnothelia. Our study provided a more comprehensive distribution range and chemical variation for each species in Bulgaria. A new chemotype is described for C. rangiformis, containing atranorin, fumarprotocetraric, psoromic, rangiformic and norrangiformic acids. This one is rarer than the other chemotypes of the species. Phylogenetic analyses based on ITS rDNA, IGS rDNA and rpb2 were carried out to confirm the identity of C. magyarica in Bulgaria. Additionally, ITS rDNA of other species was also sequenced to confirm the identifications. A new key to all the Cladoniaceae taxa known from Bulgaria is included. Key words: Lichenized Ascomycota, Bulgarian mycota, ITS rDNA, Lecanorales, macrolichens, Mediterranean region, secondary metabolites.