Unequal exchange is seen as an extension of the transformation of labor values to production prices as encountered in the traditional Marxist analysis. The deviation between price and value is identified as a symptom as well as a cause of unequal exchange. The view that developed countries export less value to their less developed trading partners provides an empirical content to the theory of unequal exchange. The authors attempt to develop a model which is useful for testing whether unequal exchange exists and if so, how the magnitude of surplus value transfers can be measured.