Cellulose nanocrystals (CNC), derived from large renewable forest and other biosources, have been of growing interest in the formation of polymer nanocomposites. Recently, we reported that the quality of dispersion of CNC in PLA systems is enhanced substantially by the use of spray freeze dried CNC (CNCSFD). This enhancement is attributed to the observed high porosity and network structure of CNCSFD. The presentation will report the results of studies to evaluate the characteristics and behavior of nanocomposites obtained by the incorporation of CNCSFD in low and high density polyethylene resins. The effect of CNCSFD on the quality of dispersion and on the crystallinity and thermal and mechanical properties of the resins will be discussed. These characteristics will be compared to the behavior of composites prepared with the same polyethylene resins using clay and other commercial CNC particles.