Four crude oil and core samples were recovered from four oilfields located in Abu Gharadig basin in the North Western Desert, Egypt. The samples were geochemically assessed in order to understand their genetic relationships for determination of source rock quality. API and sulfur contents, n-alkanes, isoprenoids, and Rock Eval pyrolysis were done. The results show that Abu Gharadig oil samples are of marine origin; their source rocks are rich in clay content and were deposited under reducing conditions. Also, these oils have a high maturity level. On the other hand, the source rock samples are reaching to the peak of the oil window for hydrocarbon generation, with a high maturity level and derived from marine organic sources, and show no biodegradation or water washing. This explains much of the chemical and physical properties uniformity observed across crude oil and source rock samples in the basin.