Weathering grades and depths are some of the most important geo-engineering properties determining the cost, efficiency and reliability of engineering projects. As weathering properties are heterogeneous and anisotropic it is assumed that electrical resistivity tomography (ERT) techniques, which have been used for various subsurface surveys, can be used to gain more subsurface data which are also reliable from the view of weathering. Therefore in this study, ERT techniques were applied to identify the weathering properties of ultramafic rocks in Bursa, Turkey. The weathering grades were identified by field and laboratory studies. ERT studies were carried out in three lines with electrode spacing of 0.5m and 2m. Sixty electrodes were deployed for each of the lines. During ERT studies both Wenner and dipole-dipole configurations were carried out. According to the data obtained, it is concluded that the inversion model sections of the Wenner configuration show better correlations with the weathering properties. It is also noted that the use of ERT techniques supplies fast and reliable data for wider subsurface areas from the view of weathering. © 2011 ARMA, American Rock Mechanics Association.