Abstarct: Abstract: In this study, the geochemistry of 9 oil seeps in Lorestan zone has been studied by elemental geochemistry, isotopic geochemistry and organic geochemistry (gas chromatography and gas chromatography-mass spectrometery). The main purpose of this study was to investigate the geochemical properties of these seeps, determine their sources, and examine their relationships with four crude oil samples from the formation reservoirs of Ilam and Sarvak in Maleh-Kuh fields and three samples from the source rocks of Garau, Surgah, and Sargelu formations in Anjir and Babahabib fields were employed for correlating oils. The samples recovered from the seeps were solid and semi-solid bitumen. The major portion of the extracted bitumen was separated into saturated, resin, and asphaltene fractions by liquid column chromatography (LC) and S-A-S-A analysis. The aromatic and saturated fractions were used for gas chromatography and gas chromatograph-mass spectrometry analyses, besides biomarker determination. This study also utilized the features of the carbon-13 isotope and besides the values of sulfur, vanadium, and nickel, to determine the properties of the examined seep samples and probe their relationships with the oils of the reservoir and source rocks. This source and relationship determination was fulfilled by the examination of the depositional environment of the oil-generating source rocks, oxidation-reduction conditions, maturation degree, age, and rock lithology. The variations in the carbon isotope values of the saturated (δ 13Csat) vs. aromatic (δ 13Caro) compounds indicated the presence of a marine source rock for the examined samples of this study. Likewise, the variations in the sulfur element against the V/(V+Ni) ratio, besides the vanadium against nickel variations, revealed mixed marine-continental source rocks and sub-oxic conditions for the examined samples. The carbon-13 isotope rates of the saturated compounds (δ 13Csat), besides the Pristane-to-phytane isoprenoid values, determined the age of the sample-generating source rock at Upper-Jurassic till the late Cretaceous. This finding corresponded to the results of some biomarkers, such as the C28/C29 stranes ratio and oleanane index. The isoprenoid-normal alkane diagram (Pr/nC17- Ph/nC18) showed that the probable source rock generating these samples was deposited in the reduced environment and derived from kerogen type II and, minimally, from kerogen type II/III. This diagram also revealed that biodegradation impacted the samples of seep 31, 36, 29, 20, and 34, disclosed by the chromatography of the mentioned samples as well. The Carbon Preference Index (CPI) ranged from 0.93 to 1.39 in the examined samples and indicated their relative maturity. The radar chart developed baxsed on seven biomarker ratios displayed no similarity in the design of most seep samples. Only did the seep samples of 29 and 33, as well as those of 28 and 30, show close similarities, which could be attributed to the interrelationship of these two seep pairs. A comparison of the patterns derived from radar charts revealed that the oil seeps 29 and 33 closely resembled the reservoir oils of Ilam and Sarvak and source rocks of Garau and Surgah, indicating the relationships of these samples with Ilam and Sarvak reservoirs and Garau and Surgah source rocks.