Dictyopteris prolifera, a marine algae (Phaeophyceae) native to Asian waters (Japan), has been collected recently on the western coast of the Baja California Peninsula, Mexico. Its finding represents the first record of this non-indigenous species on the Mexican Pacific coast, which also means a new record for American waters. Dictyopteris prolifera was found in June and September 2010, growing attached to rocks in the intertidal zone at Punta Morro Redondo, Cedros Island in Baja California, Mexico. Direct observations in the field about its abundance and size showed that D. prolifera has established as a permanent species. The mean length of specimens of this population is ~25 cm. Results of a monitoring programme show an increasing record of non-indigenous species on the coast of Baja California, mainly derived from ship traffic.