A large increase in the crystallization temperature of low density polyethylene (LDPE) when blended with high density polyethylene (HDPE) is reported. Such behavior is observed for quenched LDPE rich blends when the low melting component is cooled from 119 degrees C under controlled conditions in the differential scanning calorimeter. It is suggested that the presence of the most linear LDPE methylene segments within the HDPE-rich crystals (cocrystallization phenomenon) facilitates the nucleation of the more branched LDPE segments on cooling. On reheating, a depression in the low melting temperature component (LDPE) is observed with increasing HDPE content in the blend.