Nine crude oil and 15 core samples from the North Slope were analyzed by geochemical methods to identify relationships between the oils and their source rocks. Based on bulk geochemical parameters, the crude oils can be separated into the two groups reported by Magoon and Claypool (1981): a Barrow-Prudhoe group and a Simpson-Umiat group. One exception to this classification is an oil produced from the Cretaceous Kongakut Formation at South Barrow that has some features of each type and may be a mixture of the two. Standard geochemical techniques were used to evaluate the oil-source potential of rocks from Cretaceous to Permian age. These data identify the pebble shale unit of the Cretaceous Kongakut Formation, the Jurassic Kingak Shale, and the Triassic Shublik Formation s having the most favorable oil-source potential. Gas chromatography-mass spectrometry (GC-MS) of steranes and terpanes was used to correlate oils with potential source rocks. Based on these results, both the pebble shale unit and the Cretaceous Torok Formation are suggested as possible sources of the oil from the Umiat Basin and Simpson shelf. A positive correlation could not be made for source rocks of the Barrow-Prudhoe oils, although based on pristane/phytane ratio the Triassic Shublik Formation is suggested as a possible source.