A taxonomic revision of the genus Syntrichia Brid. (Pottiaceae, Musci) in the Mediterranean Region and Macaronesia has been carried out, thus contributing to knowledge of its distinguishing morphological characters, geographic distribution and nomenclature. Some 3000 specimens, including the most of type material, were studied. An identification key, morphological descriptions, photographs and numerous observations on taxonomic and nomenclatural problems of the 23 taxa accepted in the study area, are provided. New records for some countries of the Mediterranean basin and Macaronesia are given. Five new synonyms are proposed. The designations of 11 new lectotypes are included and the name Syntrichia aciphylla var. calva J.J. Amann is excluded from the genus Syntrichia.