Low frequency pressure oscillations in a research ramjet combustor have been studied using an integral technique. The analysis deals with plane one-dimensional oscillations with a two-dimensional mean flowfield. The flowfield in the dump combustor consists of three parts: a flow of reactants, a region containing combustion products, and a recirculation zone. separated by a flame sheel and a dividing streamline. Each region is treated separately and matched with the other. Acoustic fields in the inlet section and in the combustion chamber are coupled at the interface to determine the complex wave number characterizing the linear stability. Good agreement with experimental results has been demonstrated.