The conservation status of the communities of the class Asplenietea trichomanis was studied in 2010 in southern Poland. In all, 81 sites with rocky plant communities were selected, and 270 phytosociological relevés were collected. Alien species were found at 27% of the sites. This indicates that the rocky communities there are exposed to strong pressure of plant invasion. The most common alien species was the neophyte Impatiens parviflora, which occurred at 25% of the sites and 12% of the relevés examined. Robinia pseudoacacia was also locally invasive, especially on partially shaded serpentine rock. The other alien plant species were found only locally and in small numbers, and are not invasive at this time.