The melting of binary mixtures of low molecular weight fractions of linear polyethylene and of poly(ethy1ene oxide), crystallized in such a manner that cocrystallization does not take place, is considered from both a theoretical and experimental point of view. Utilizing the appropriate Flory-Huggins mixing expression for species that are chemically identical and assuming that the crystalline phase is pure, a melting temperature-composition relation is derived. This relation gives good agreement with new experimental results that are presented. Other melting temperaturHomposition relations that have been previously used to analyze this type of data are discussed in their proper perspective. The requirements that need to be satisfied by the mixture components are pointed out.