Biomarkers study is one useful tool for oil-oil and oil-source correlations in any petroleum field. Molecular markers were used together with stable carbon isotopes to constrain genetic relationships between oils and potential source rocks in the Marun oil field. The Marun oil field is one of the giant oil fields in south west of Iran. It consists of two oil reservoirs named Asmari and Bangestan. This article presents the correlation of Asmari and Bangestan oil reservoirs with probable source rocks named Pabdeh, Kazhdomi, and Garau formations. Distribution patterns of different biomarkers, such as Hopanes and Steranes (obtained by gas chromatography-mass spectrometry), were used to correlate oils and source rocks. The results show that there is an obvious similarity in distribution patterns of all biomarkers between Kazhdomi formation and oil samples as compared with Pabdeh and Garau formations. Furthermore, stable carbon isotope shows that in contrast to Pabdeh and Garau formations, the carbon isotope range of Kazhdomi formation had a good overlaying with Asmari and Bangestan oil reservoirs. The result of this study shows Kazhdomi formation as a proper source rock of oil in the Marun oil field.