Petroleum pollution is an important environmental problem in countries with oil industry such as Iran. In addition to the harmful effects on human health, petroleum pollution might influence soil and water resources and natural ecosystems and, therefore; adversely affect living organisms, especially plants. This study was carried out to investigate the level of petroleum pollution and its effects on soil physico-chemical and geochemical properties as well as magnetic susceptibility and heavy metals concentration in Tehran Oil Refinery region. Micromorphology and clay mineralogy of soil, were also examined. Polluted locations with various soil oil content (total petroleum hydrocarbons, TPHs in the range of 2?14%) and adjacent non-polluted location were selected in the study area around the Tehran Oil Refinery. The amount of contamination of the samples was measured by Soxhlet extractor. Also, the impact of soil petroleum pollution on some physico-chemical soil properties including EC, pH, CCE and OM was evaluated. Soil texture parameters were also measured using laser diffraction particle size analyzer and the effect of TPHs on these characteristics was evaluated. The relationship between hydrocarbon pollutants and magnetic susceptibility and concentration of heavy metals in polluted soils was determined. Soil magnetic properties were measured at two frequencies of 0.46 and 4.6 kHz and heavy metals was extracted using 6.0 N nitric acid. Other important soil characteristics measured and evaluated in this study included soil hydraulic conductivity (constant-head method) and soil hydrophobicity (the molarity of ethanol droplet method) of contaminated and non-contaminated soils. Based on the results, oil pollution has affected on physico-chemical, hydraulic and geochemical properties of soils. Sandy behavior in the soils of this area along with significant increase in hydrophobicity and increased hydraulic conductivity of soil, seem to reduce water retention and increase the water movement in soils. This causes the water to pass through the root zone and water use efficiency decreases in agricultural land. It was also observed that the magnetic properties of the samples did not increase in the presence of contaminants. This is probably due to the fact that hydrocarbons are diamagnetic. Also, petroleum pollution with TPHs higher than 11% seems to be the critical level of contamination of heavy elements in the study area. The concentration of heavy metals in polluted soils has significantly increased compared to the amount of heavy metals in non-polluted soils. Key Words Petroleum hydrocarbons, Magnetic susceptibility, Hydraulic conductivity, Soil hydrophobicity, Heavy metals, Clay mineralogy