A detailed organic geochemical study; utilising petrography, biomarker hydrocarbon analysis and high temperatureGC analysis of extractable wax hydrocarbon constituents was performed on four marginally oil window-mature sourcerocks from the Shahejie Formation (Eocene), Damintun depression in eastern China. The main maceral components inthe source rocks were vitrinite, liptinite and exinite, with vitrinite being more abundant (>50 vol.%) in organic-leansamples whose TOC contents were between 1 and 2 wt.%. Large differences in pristane/phytane ratios suggested thatthe organic-rich samples were deposited in a less oxic depositional environment than that for the organic-lean rocks.The distribution of extractable wax hydrocarbons, determined by high temperature GC, showed a marked differencebetween these two sample types. The organic-rich samples contained high molecular weight hydrocarbons (HMWHCs)dominated by macrocrystalline n-alkanes (n-C23–n-C37, typically maximising at n-C29), while the organic-lean samplescontained lower amounts of extractable wax hydrocarbons but were relatively rich in microcrystalline components (>n-C35). In all source rocks (Es3 and Es4), a noticeable odd-over-even predominance (OEP) of n-alkane chain lengths(up to n-C65) was evident, consistent with a direct biological origin for the long n-alkyl chains. They were mostprobably formed during diagenesis from decarboxylation of predominantly even-carbon-numbered aliphatic acidsoriginating from higher plant or lacustrine algal sources and/or were directly biosynthesised in hydrocarbon form. Atleast two other homologous series of branched/cyclic HMWHCs were observed, one of which was confirmed as a seriesof branched alkanes (probably methyl-branched). The carbon number distribution patterns of HMWHCs may be primarilycontrolled by thermal maturity and biogenic source input as well as being influenced by diagenetic reactionsgoverned by depositional environmental conditions, as shown previously [Carlson, R.M.K., Teerman, S.C., Moldowan,J.M., Jacobson, S.R., Chan, E.I., Dorrough, K.S., Seetoo, W.C., Mertani, B., 1993. High temperature gas chromatographyof high wax oils. In: Indonesian Petroleum Association, 22nd Annual Convention Proceedings. Jakarta, Indonesian,pp. 483–507. Carlson, R.M.K., Jacobsen, S.R., Moldowan, J.M., Chan E.I., 1994. Potential application of hightemperature gas chromatography to Middle Eastern petroleum exploration and production. In: Al-Husseini, M.I.(Ed.), Geo'94, Vol 1., Selected Middle East Papers from The Middle East Petroleum Geoscience Conference, 1994; Gulf PetroLink. Manama, Bahrain, pp. 258–267]. Our study indicates for the first time that Es3 source rocks as well asEs4 facies contain HMWHCs. The distributions of extractable wax hydrocarbons suggest that both Es4 and Es3members may potentially serve as important parent source rocks for generating waxy petroleum in this region.