The prospect of inadequate future supply of natural gas, natural gas liquids, and petroleum oils has stimulated considerable interest in the utilization of the large reserve of high grade Green River formation oil shale. Although much information on the production and refining of crude shale oils has been published, little is known of the value of crude shale oils as a source of fuel gas, low-molecular weight olefins, aromatics and pitch. A 2 1/2 inch inside diameter tubular flow reactor was employed to study the pyrolysis of crude Green River shale oils at atmospheric pressure, using steam for atomization of the feedstock and for control of the partial pressure of the product gas in the 0.2 to 0.8 atmosphere range. At pyrolysis temperatures from 1400 to 1550 F and reaction times from one to 4 1/2 seconds approximately 50 percent of gaseous products were formed. Carbon formation varied from one to eleven weight percent, with the remaining nongaseous products consisting primarily of liquid aromatics and pitch. It is demonstrated that the pyrolysis product yields of Green River shale oils are very similar to those obtained from petroleum oils of equal carbon-hydrogen weight ratio in spite of significant differences in composition. Gaseous product distribution are shown to agree closely with the generalizations developed from natural gas liquid and petroleum oil pyrolysis data obtained over an equivalent range of reaction conditions.