The phylum Bryozoa is one of the less studied macroinvertebrate groups in the Slovenian coastal sea. However, these animals play an important role in marine coastal ecosystems, especially as bioconstructors and filter feeders. Non-indigenous species represent five to ten percent of all Mediterranean bryozoan species. In this paper, we present an updated list of non-indigenous or cryptogenic bryozoan species recorded in Slovenia. The list includes six species: Amathia verticillata, Bugula neritina s.l., Celleporaria brunnea, Tricellaria inopinata, Watersipora arcuata and Watersipora subtorquata with comments on their morphology, ecology and distribution in the Slovenian coastal sea. Introduction vectors and possible dispersal mechanisms are discussed, as well as methodological approaches and problematic areas as regards the study of non-indigenous bryozoans. Three species reported here, A. verticillata, C. brunnea and W. subtorquata, represent the first confirmed record from the Slovenian Sea.