There is growing interest in using cellulose nanocrystals (CNC) as nanofillers in the preparation of polymer nanocomposites. Since biodegradable, biocompatible CNC is derived from renewable biosources, much of the effort has been directed toward using it as the nanofiller with other bio-based polymers such as poly(lactic acid) (PLA). However, it would also of interest to explore the potential for incorporating CNC with other polymers such as polyethylene to produce viable polyolefin/CNC nanocomposites. While other methods such as solvent or water assisted processing techniques might be considered, it is commonly preferred to employ melt processing methods for economic and environmental reasons. The presentation will report on the status of our efforts to prepare nanocomposites by incorporating CNC in both high density polyethylene (HDPE) and linear low density polyethylene (LLDPE). Initial results indicated the need for reducing the size of feed polyethylene pellets to insure large surface contact areas between PE and CNC in the early stages of mixing. Moreover, effective premixing in the solid state was helpful in enhancing the uniformity of the nanocomposite. Morphology examination using scanning electron microscopy (SEM) of the various components and the CNC suggested that the porosity and network structure of the spray freeze dried CNC (SFDCNC) were effective in producing an interconnected reinforced network of polyethylene and CNC. This was most prominent at concentrations above the percolation level, where various rheological and mechanical properties showed significant changes. The results of WAXD and DSC showed that the crystallinity and crystallization kinetics of the two polymers were influenced to different levels by the presence of CNC. However, the optical transmittance of the nanocomposites was similar to that of the matrix resins. Other observations will be discussed.