Industrial activities have led to the discharge of a wide range of hazardous chemicals in soils, such as coal tars which are always composed of hundreds of organic compounds (PAHs, BTEX,…), but also of some inorganic compounds. Environmental hazard assessment of soils contaminated with coal tar are generally investigated by a multidisciplinary approach coupled chemical and ecotoxicological analysis. However, a direct correlation between chemical analysis and results of ecotoxicological bioassays is generally not observed. The aim of this work is to deepen the relationships between PAHs concentration and ecoscores caculated from a battery of specifically selected bioassays including solid and liquid phase bioassays (Lors et al., 2010 & 2011). First, PAHs distribution is measured on several fraction of soils, and, second, parameters governing the release of PAHs to soil water are investigated by microscopic techniques.