<em>Abstract</em>.—Atlantic sturgeon <em>Acipenser oxyrinchus</em> are consistent visitors to specific areas of Long Island Sound and the lower portions of Connecticut rivers despite the fact that natal stocks have been extirpated. Atlantic sturgeon have been collected annually in the Connecticut River from 1988 through 2004. Similarly, annual utilization of selected areas in Long Island Sound points to the importance of these areas, probably as foraging sites. By means of pumped gastric lavage, 41 Atlantic sturgeon collected in Long Island Sound in October 2001 were examined to determine the prey items consumed. Ninety-three percent of the fish examined showed evidence of recent feeding. Among the fish that had fed, polychaetes (<em>Pherusa</em>, <em>Glycinde</em>, and <em>Clymenella </em>spp.) comprised 52% of stomach contents on average and all fish had consumed worms (range, 1 to 177). Polychaetes accounted for 2-100% of stomach contents by number and 63% of the diet by weight. Decapods (<em>Squilla</em>, <em>Gilvossius</em>, and <em>Upogebia</em> spp.) were also a prominent prey item, having been eaten by 63% of the fish that had fed. The number of these three mud shrimps eaten ranged from 0 to 49 (mean, 11/fish) and comprised up to 75% of the diet by number and up to 97% by weight (mean, 41%). Other prey included amphipods and pea crabs <em>Pinnixia</em> spp. Eleven subadult Atlantic sturgeon (<2 m total length) collected in the Connecticut River from 2000 to 2002 were also lavaged for stomach contents. Food was obtained from 73% of the fish examined; stomach contents were dominated by polychaetes <em>Scolecolepides</em> spp.