he current study aims to document evapotranspiration and associated surface energy fluxes for rainfed annual crops within a Mediterranean hilly agrosystem, in order to provide information on crop water use under such little-studied conditions. For this, an experimental study is conducted within the Tunisian study site of the OMERE observatory (French acronym for the Mediterranean Observatory of Water and the Rural Environment), located in the north-eastern Cap Bon peninsula. It relies on eddy covariance (EC) measurements at the plot scale. We report that (1) observations are consistent with previous studies under Mediterranean or semi-arid contexts, with time series of energy fluxes that depict classical seasonal dynamics, (2) common flux ratios (i.e., Bowen Ratio, ratio of actual to reference evapotranspiration) may change according to upwinds and downwinds, which requires further investigations about possible changes in aerodynamic conditions, and (3) a reference evapotranspiration value of 4 mm day−1 seems to be a threshold beyond which actual evapotranspiration decreases systematically and rapidly. In terms of agricultural water management, the current study suggests to look for early sowing species/varieties, in order to reduce the evaporation-based water loss in autumn. Overall, EC measurements seem promising over rainfed annual crops within semiarid hilly agrosystems, for long term observations, environmental modelling and operational purposes. Since the current study is conducted over few small fields within a specific hilly topography, the original results we report here need to be strengthened with complementary studies.