Conventional organic geochemical and biomarker parameters are used together to provide information on source organic matter input, depositional environment, and the correlation between crude oils from different pay zones and geographical locations in Egypt. The method of biomarker characterization is based on the fractionation of crude oils by liquid chromatography into three main compound classes: saturated hydrocarbons, aromatics and N, S, O components. The identities of specific compounds and the carbon number distribution of n-alkanes and acyclic isoprenoids were determined by capillary column gas chromatography. On the basis of correlation plots between biomarker and nonbiomarker parameters, the oil samples are classified into three main groups. The first group includes oil samples from the central part of the Gulf of Suez (Balayem Land, Bakr, Gharib and July fields) and is typical of crude oils generated in a strongly reducing environment. The second group comprises oils generated from sediments deposited in suboxic conditions and includes oils from the south central and southern part of the Gulf (Ras Fanar, Shark El-Zeit, Amal 9, Amal 10 and Gamma) and Yidma crude from the Western Desert. The third group includes oil samples of the Western Desert from the Umbaraka, Khalda and Meleiha fields, which are typical of oils accumulated under oxic palaeoenvironmental conditions.