The Middle Eocene sequence in the Darende-Balaban Basin (Eastern Turkey) characterized by shallow and deep marine benthic and planktonic foraminiferal assemblages. Nummulites and other benthic foraminifers are common in its lower part (mainly in the conglomerates and sandstones) while the planktonic foraminiferal assemblages are abundant in middle and upper parts (generally fine-grained sediments). Acarinina bulbrooki Zone is identified within Middle Eocene strata in the study area. This biozone correlated with other Mediterranean, southern mid- to high-latitude successions where some similar species are recorded. Paleontological and sedimentological data presented in this study suggest that the Middle Eocene sequences are dominated by siliciclastic and carbonate sediments that were deposited in various environments ranging from very shallow (Korgantepe, Asartepe and Darende Formations) to deep marine (Yenice Formation) ones.