There are several problems dealing with oil-contaminated soil that affects environmental quality and change the geotechnical properties of the soil. Soil contamination is a detriment to the foundation and structures on it. Therefore, in this paper, a series of experimental model tests has been carried out to evaluate the ultimate lateral capacity and lateral deflection of a single pile embedded in clean and oil-contaminated sand slope. Contaminated sand layers were used at thickness equal 0.3 pile length (LC=0.3LP) and prepared by mixing the sand with an oil content of 4% (O.C=4%) with respect to the dry weight of soil to match the field conditions. The investigations are carried out by varying the relative density of sand (Dr), The distance of the pile head from the slope crest (X), the vertical length of slope (LV) and agradient of slope (θ). It was found that the load-lateral deflection behavior and ultimate lateral capacity of the pile can be drastically reduced by increasing vertical length of slope. The relative density of sand and slope gradient are significant factors affecting the ultimate lateral capacity of piles embedded in oil-contaminated sand slope. The ultimate lateral capacity is decreased and the lateral deflection of the pile is increased with closeness from slope crest.