Forty species of benthic hydroids, belonging to 15 families and 21 genera, were found in a collection, obtained by SCUBA diving, from the Maltese Islands. Paradoxically for the well studied Mediterranean region, the hydroid fauna of these islands is virtually unexplored. Of 40 species, 33 were identified to species level, with 28 of them reported for the first time for the study area. Hydractinia monocarpa is recorded for the first time in the Mediterranean Sea, and a presumed new species of the genus Clytia has been found. The most speciose families are Campanulariidae with 10 species (25%), Aglaopheniidae with six species (15%) and Sertulariidae with five species (12%). Aglaophenia and Clytia are the most diverse genera, both with six species (15%). A problem with respect to subspecies of Sertularella ellisi is resolved based on nematocyst observations. In terms of geographic distribution, eight species (24%) are endemic to the Mediterranean Sea, this number increases to 16 species (48%) when including those restricted to Mediterranean and nearby Atlantic waters, whereas the remaining species have wider distributions.