Non-Newtonian flow behaviours of dilute and semi-dilute carboxymethyl cellulose (CMC) solutions in the presence of spindle-shaped cellulose nanocrystal particles (CNC) were investigated. Scanning transmission electron microscopy, dynamic light scattering, polarized optical microscopy, and turbidity measurements of CNC suspensions in CMC solutions were also carried out. Adding CNC particles only within the range of 0.33-2.0m(3)/m(3) into the dilute and semi-dilute CMC polymer solutions increased the viscosities at low shear rates between 10(3)-10(5) times. The flow curves of CNC suspensions in CMC polymer solutions turned highly non-Newtonian, and their viscosities at high shear rates (>10(3)) still converged to the flow curves of CMC solutions. The viscosity increase comes from the nematic flocculation of CNC particles in the presence of a non-adsorbing CMC polymer which results in CNC flocs with water entrapped pockets.