The influences of branch content (BC) and composition distribution (CD) of hexene linear low-density polyethylene (LLDPE) on its miscibility with low-density polyethylene (LDPE) were investigated. Ziegler-Natta (ZN) and metallocene-LLDPE (m-LLDPE) were used to study the melt miscibility using theological tools. Dynamic, steady shear and transient measurements were carried out in an ARES rheometer at 190degreesC. The miscibility was revealed by the dependence of their eta(o), eta'(omega), G', and N-1(gamma) over dot on blend composition. The CD of LLDPE has influenced its miscibility with LDPE. The ZN-LLDPE blend with LDPE was found to be more miscible than an m-LLDPE of the same M-w and similar BC. On the other hand, a high-BC m-LLDPE (32.2 CH3/1000 C) was found to be more miscible with LDPE than a low-BC m-LLDPE (14.4 CH3/1000 C) of the same M-w and MWD. The high-BC m-LLDPE blends with LDPE were partially miscible and immiscibility is likely to develop in LDPE-rich blends. Agreement was observed between the measured theology and theoretical predictions of Einstein, Scholz et al., Palierne, and Bousmina emulsion models. (C) 2003 Elsevier Science Ltd. All rights reserved.