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Leaf area index (LAI) is very used to reveal the vegetation situation. To estimate the LAI for cereal, both direct and indirect methods have been used. In particular, remote sensing is a fast and reliable technique to develop the LAI estimation models. In this work, we present the potential of Sentinel 1 images for cereal estimation LAI in the center of Tunisia under semi arid climate. We established a statistical relationship between field LAI measurement for irrigated and rainfed wheat and backscatter coefficient based on an empirical analysis. This will be very useful in order to predict the water stress in a subsequent step. For experimental validation, the LAI of wheat crops were determined through the crop growth stages using eight Sentinel-1 images. The results showed a significant correlations, for the irrigated wheat, between LAI and backscatter coefficient for VV polarization (r values of -0.7) and for HV (r value of -0.5). For the rainfed wheat only the VV polarization showed a significant correlation (r= 0.6).