The influence of the mole fractions and the chemical nature of the short branches on the level of crystallinity and on the melting temperature of functionalized polyethylene (PE) with diethylmaleate (DEM) was established. The results can be interpreted to yield two interesting points: the participant sequences in the crystallization decrease with the degree of grafting, which seems to indicate that the functionalization occurs at random, confirming evidences reported in the literature about the insertion on the secondary carbons. On the other hand, the study of the equilibrium melting temperatures, indicated that, the grafting increase the number of branches but not in a purely random arrangement. This last point clarify previous evidences obtained by FTIR, that report that grafting at the beginning of the reaction proceeds by radical attacks on the terminal unsaturations.