Three alien Rhodophyta, Botryocladia madagascariensis, Hypnea anastomosans and Hypnea valentiae, were recorded and illustrated for the first time from Greece (Aegean Sea and nearby areas). Previously reported from Karpathos Island, B. madagascariensis was observed from Korinthiakos Gulf. Reported as H. esperi from the Mediterranean coast of Israel, H. anastomosans was recorded from the Saronikos Gulf and Rhodes Island. Lastly, the occurrence of H. valentiae in the Eastern Mediterranean basin was confirmed. Habitat, taxonomical comments, and geographical distribution were provided for each species. A critical review of Hypnea species occurring in the Mediterranean Sea was also provided.