On the bottom of the circalittoral zone of the Mediteranean Sea, prevalently calcareous algae, and subordinately bryozoans, sponges and serpulids give rise to bioconstructions called Coralligenous (algal reef). It with different aspects, mostly columnar or dome-shaped, and different zoo-phitological compositions represent a true biodiversity hot spots on the sea bottom. Ostracod and foraminifer do not participate directly in the construction of the reef but they can contribute significantly to the increase in its degree of biodiversity. The present study wants to be the first attempt to analyze the composition and structure of the microfaunas associated with bioconstructions in an area located along the Ionian coast of SE Sicily offshore Marzamemi (SR, Italy). For this purpose, seven samples, picked up from the surface of the bioconstructions, were collected between 33 and 37 m depth using the sorbona sampling device. Living ostracod associations include 22 taxa: clearly dominant are the specimens belonging to the genus Xestoleberis, followed by the genera Neonesidea, Tenedocythere, Aurila, Loxoconcha, Urocythereis; poorly represented are the genera Carinocythereis, Paradoxostoma and Polycope. Foraminifers associations are almost exclusively represented by benthic phytal taxa and include over 3700 specimens belonging to 130 different taxa. The families quantitatively prevalent, both in terms of richness of species and abundance, are Elphidiidae, followed by Hauerinidae, Cibicididae, Ammoniidae, Homotrematidae, Planorbulinidae, Textulariidae, Cribrolinoididae, Asterigerinatidae, Rosalinidae, Spiroloculinidae and Globigerinidae that are subordinate, while little represented are Astrononionidae, Haplophragmoididae, Polymorphinidae, Ammodiscidae, Ellipsolagenidae, Spirillinidae etc.