A comprehensive monthly trawl survey of Maryland and Virginia's Sinepuxent and Chincoteague Bays found 65 species of fishes within 40 families and 59 genera currently occupying these two seaside bays. Twenty-three species were new to the fauna which, since 1876, now totals 99 species. Various methods, beach seining, crab potting, hook and line fishing and wire oyster test trays, were employed to capture smaller species. An annotated list of species, as well as comments regarding seasonal population dynamics, size ranges, ecological requirements or preferences, are presented. Fish distributions, hydrographic conditions and invertebrates, mainly crabs, squids and Aurelia illustrate the predominant use of the southern inlet as an avenue of entry into these bays. The establishment of the newer northern inlet at Ocean City, Maryland, has had a profound influence on the hydrography of Sinepuxent Bay. This has resulted in extinction, entry or reduction of various fish species. Little use is made of the northern inlet as an avenue of entry into Chincoteague Bay. The fishes and crabs that do enter Sinepuxent Bay by way of the northern inlet are currently not found beyond the 5-8 mile southward influx of water from that inlet. The permanent establishment of the present northern inlet to Chincoteague Bay, via Sinepuxent Bay, in 1933 (Md. Cons. Dept. 1933) along with the economic development of the Ocean City, Maryland area places a greater demand on the need for increased knowledge of the fishes of this area and the effects of these inlets on species abundance, presence or distribution. Although Giovanni da Verazzano accidentally sailed into Chincoteague Bay in 1524 (Covington, 1915), it was not until 1876 (Uhler and Lugger, 1876) that the first contribution of 12 species of fishes was collected from these waters (Fig. 1). Seven additions to this list of fishes were made by Lugger (1877, 1878) who sampled the southern inlet at Chincoteague, Virginia. Goode and Bean (1879) added two more species to the list. Fowler (1913-45) in a series of nine papers and sporadic surveys, primarily at Chincoteague and Franklin City, Virginia, and Ocean City, Maryland, listed 51 additional species to extend the total to 72 then known from Sinepuxent and Chincoteague Bays, Maryland and Virginia, and their inlets (Table III). Murphy (1960) recorded three commercial species in the early catch records of these bays. Arve (1960) trap netting in Chincoteague Bay, north of South Robin Marsh, recently added two species to the list of fishes known previous to 1959. Dillon (1960) notes the sport fishery and species about Ocean City, Maryland. No comprehensive study of the fishes or their distribution and seasonal abundance within the entire length of the bays has ever been attempted. 1 Contribution No. 161, Maryland Department of Research and Education, Solomons, Maryland.