Abstract: The aims of the present investigation were to study the feature of biotic environment of oyster beds and to study quantitatively the biodiversity of fauna and flora living within these habitats. Eighteen selected oyster beds, within the Exclusive Economic Zone of Qatar were investigated by scuba diving. Most of the oyster beds were found in the area with sandy-rocky and Coral blocks bottom forms. Pearl oysters abundance varied widely between the different beds and within the same beds due to the variations in the bottom substrates. The associated biota was composed mainly of Algae (4%), Porifera (3%), Cnidaria (8%), Polychaeta (4%), Echinodermata (13%), Mollusca (55%), Chordate (2%) and Crustacean (11%). The comparison of our findings on the occurrence and distribution of marine biota to previous studies has shown similarities between Qatar and other Gulf States particularly Saudi Arabia and Bahrain.