Bat distribution data is incomplete for the delta region of Arkansas. We extensively surveyed 16 counties within the Mississippi alluvial plain that comprises the delta from late spring to early fall 2004 using mist nets. We obtained 44 new county records for 9 species: Myotis lucifigus, M. austroriparius, Pipistrellus subflavus, Eptesicus fuscus, Lasiurus seminolus, L. borealis, L. cinereus, Nycticeius humeralis, and Corynorhinus rafinesquii. We generated updated distribution maps for these species and eastward Arkansas range expansions were documented for L.seminolus. Possible sampling concerns and research directions are discussed in relation to the needs of bats inhabiting bottomland forests of the delta, particularly M. austroriparius and C. rafinesquii