The aim of this work was the study of blends of linear low density polyethylene (LLDPE) and an ethene-propene-l-butene terpolymer (t-PP). Two types of polyethylene were used to prepare the blends: an ethene-co-l-hexene (LLDPE(H)) copolymer and an ethene-co-l-octene (LLDPE(O)) copolymer. These copolymers present similar comonomer contents, molar mass, molar mass distribution and catalyst systems, but differ in their comonomer distribution. The blends were obtained through mechanical mixing using a single screw extruder at different compositions: 20, 40, 50, 60 and 80 wt.% of LLDPE. From DSC measurements two separated melting and crystallization peaks were observed and dynamic mechanical analysis showed two glass transitions indicating that LLDPE/t-PP blends are immiscible in amorphous and crystalline phases in the solid state. X-ray diffraction showed that the unit cell parameters of both polymers in the blends remain unchanged independent of the composition of the blend. (c) 2004 Elsevier Ltd. All rights reserved.415894902