Hemodynamics plays a major role in the development of numerous diseases and disorders, including atherosclerosis and stroke. Hemodynamic forces must be adequately mapped to precisely predict and avoid various illnesses and disorders. Blood is a complicated biological fluid that contains constituents, such as erythrocytes that cause it to behave in a non-Newtonian manner. This component is usually overlooked while studying carotid blood flow, and blood is modeled as a Newtonian fluid with constant viscosity. In the present study comparison of hemodynamics in carotid artery for Newtonian viscosity model and non-Newtonian Carreau-Yasuda (CY) viscosity model is done. Computational fluid dynamics analysis is carried out for four patient-specific healthy carotid artery models. The geometry of the carotid artery is obtained from a CT scan and a 3D model is generated using MIMICS. Blood enters the carotid artery through a common carotid artery (CCA) and splits into two arteries named internal carotid artery (ICA) and external carotid artery (ECA). The pulsatile velocity boundary condition is considered at CCA, and the pulsatile pressure boundary condition is considered for both ICA and ECA. The results obtained for both Newtonian and Carreau Yasuda's viscosity models are studied and compared. Wall shear stress is calculated and when compared, results obtained from the Newtonian viscosity model overestimates WSS in certain regions like CCA, ICA, and ECA.