The ORMEF database is a comprehensive, and robust compilation of exotic fish observations recorded in the entire Mediterranean Region from 1896 to 2020. ORMEF is composed by 4015 geo-referenced occurrences distributed in the territorial waters of 20 Mediterranean Countries and extracted from 670 scientific published papers. The resultant database is a collection of 188 fish species that are categorized by the entering mean into the Mediterranean Basin in (i) EXOTIC CAN: species coming from Suez Canal; (ii) EXOTIC HM: species introduced by a human vector, e.g. from shipping, mariculture, aquarium release or by means of other human activities; (iii) NRE (natural range expansion): Atlantic species, coming from unassisted immigration through the strait of Gibraltar. For each record (corresponding to an observation) the following parameters are reported: Species name, AphiaID (as identified by the World register of Marine Species, www. marinespecies.org), Family, Category, Year, Country, Precision of the record (that could be "Precise", "Approximate" of "Conventional"), Latitude, Longitude and the Literature corresponding source. Each record in the ORMEF database has undergone a quality check for what concerns the accuracy of the source and both geographical and taxonomic biases. ORMEF could be very helpful to inform management strategies and policymakers since it represents a new authoritative reference for Mediterranean bio-invasion research.