ABSTRACT: Petroleum hydrocarbons are used to meet a big portion of energy demand that is needed to sustain the human life. Accidental release and leakage of petroleum hydrocarbons may cause groundwater contamination and can have extremely serious consequences from both human and environmental health perspectives. Basically, petroleum hydrocarbons can be divided in two major groups. First group is called light non-aqueous phase liquids which float on water. Second group of petroleum hydrocarbons is called dense non-aqueous phase liquids and they are denser than water. Contaminations caused by light non-aqueous phase liquids can be relatively more easily remediated when compared to dense non-aqueous phase liquids and contaminations caused by dense non-aqueous phase liquids generally require application of more complex remediation technologies. There are different methods exist for the remediation of petroleum hydrocarbon contamination in the saturated and unsaturated zones ofthe aquifers. Among these, most frequently used ones are; gas/air injection, soil vapor/gas extraction, directional wells,in-well aeration, dual phase extraction, chemical oxidation, thermal treatment, fracturing enhancement and permeable reactive barrier technologies. Before the application of any method, the most important thing to do is to define aquifer and contaminant characteristics and spatial extent of the contaminant for an effective treatment process. Each one of these methods has several advantages and disadvantages that are resulted directly from properties of the contaminated aquifers. For this reason, in the petroleum hydrocarbon contaminated aquifers generally not a single method is used but a combination of two or more methods are appliedfor a more effective treatment.