The annual species of Cerastium observed in South Tyrol, C. brachypetalum, C. glomeratum, C. glutinosum, C. pumilum, C. semidecandrum, and C. tenoreanum, are treated with regard to their historical and actual geographical distribution in South Tyrol as well as of their habitat preferences. The actual geographical distribution has been worked out on the basis of a aimed mapping during the years 1999-2003. Critical aspects concerning delimitation of species are given. The results of the present study raise the question if C. pumilum grows in South Tyrol at all. At least a definitive confirmation of its occurrence is still missing. C. glutinosum has found a secondary habitat on roadsides, C. glomeratum in the intensively managed valley bottom of the Valley of Adige.