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The Middle Pleistocene environmental and climatic conditions at Asbole, lower Awash Valley, Ethiopia were reconstructed using stable carbon and oxygen isotopic composition ((13)C, (18)O) of fossil tooth enamel coupled with faunal abundance data. We analyzed the isotopic composition of a total of 80 herbivorous tooth enamel samples from 15 mammalian taxa. which archive the dietary preferences and drinking behavior from the "Asbole faunal zone". The carbon isotopic data signify a wide range of foraging strategies, across the entire spectrum of pure C4 to C4-dominated diet, mixed C3/C4 diet and C3-dominated diet. The oxygen isotopic enrichment between evaporation sensitive and insensitive taxa (epsilon(ES-EI)) is 3.7%. which provides an estimate of the mean annual water deficit of the Middle Pleistocene at Asbole of 1470 mm, a value characteristic of modern arid landscapes in this part of the Awash Valley. The isotopic data coupled with faunal abundance data indicate an arid C4-dominated open-vegetated region, with an abundance of forest-dwelling primates that identify the presence of gallery forests flanking tributary streams to the paleo-Awash River. Thus, with these combined methodologies, it is possible to explicate a more detailed character of the "mosaic" of environments characteristic of Neogene savanna ecosystems. These findings, clearly indicate the importance of avoiding oversimplification of Pleistocene environmental reconstructions, based on single proxies at isolated localities. (C) 2010 Elsevier Masson SAS. All rights reserved.