The oil of Asmari reservoirs in three oilfields in the southern Dezful Embayment comprising Parsi, Pazanan and Rag-e safid oilfields were investigated. Preliminary analyses consisting removal of asphaltene and fraction separation (saturate, aromatic, resin and asphaltene) were conducted on selected samples by column chromatography. Results indicate the dominance of saturate components in the studied oils of Parsi and Pazanan oilfields, while aromatic components dominate in the studied oil of Rag-e safid oilfield. Subsequently, normal alkanes and isoprenoids were evaluated by Gas Chromatography (GC), revealing a reducing environment of deposition for the source sediment. Ratio of Pri/nC₁₇ and Phy/nC₁₈ indicate a high thermal maturity unaffected by biodegradation processes. The ratios also indicate that the Asmari oils of the studied oilfields were generated from type II organic matter deposited in a marine environment. Evaluating C₂₇, C₂₈ and C₂₉ stranes and hopanes carried out by Gas Chromatography-Mass Spectrometry (GC-MS). The most important result is that the studied oils have shown Oleanane biomarker in their hopanograms, hence proposing their source rock to be deposited in the Late Cretaceous or younger than it (Pabdeh formation). The Carbon Preference Index (CPI) of around one, high percentage of T_s and T_m hopanes and absence of moretane biomarker, all indicate the high thermal maturity of the studied oils. It can be concluded that the oilfields in south part of Dezful Embayment have similar origin, depositional environment and hence have an identical oil family.