During the summer of 1980, EPA sponsored a large field program which was designed to gather data for developing and testing a regional scale oxidant model. Individual hydrocarbons were measured over a 30 day period in Boston, New York, Washington, DC, Baltimore, and Columbus, Ohio. The widespread nature of the hydrocarbon sampling network necessitated the participation of three gc analyses groups: Washington State University (WSU); Battelle Columbus Laboratories; and the Gas Kinetics and Photochemistry Branch (GKPB) of the Environmental Sciences Research Laboratory. In order to ensure intercomparability of results, a hydrocarbon quality assurance program was utilized. Two methods for comparison were used; the periodic analysis of synthetic mixtures and the shared analysis of ambient air samples. This report presents the results of this quality assurance program.