Representation of actual oil yields from sections of the Green River formation oil shales by two types of drill-cutting samples was evaluated. Average oil yields of single sets of mud cuttings from hydraulic rotary drilling in Colorado and gas cuttings from pneumatic rotary drilling in Utah were compared statistically with yields of core samples taken from adjacent holes. Oil yields from gas cuttings were identical to oil yields of core samples. Mud cuttings appeared to represent a section of the formation conservatively, the deficiencies increasing with increasing richness of sample. Because a large amount of the oil-yield data currently available for the Green River formation is based on mud- cutting samples, development of a valid correction method by additional testing is needed.