The carotid artery is one of the main arteries that provide blood to the brain and face. Sclerotic disorders resulting from plaque build-up in the carotid artery can increase the possibility of a stroke in a patient. This study investigates atherogenesis by carrying out a comparative study of the haemodynamic parameters in patient-specific carotid artery using Computational Fluid Dynamics (CFD) principles. The 3D model of patient-specific arteries was extracted using their Digital Imaging and Communications in Medicine (DICOM) images via MIMICS. The processing of arteries was carried out on 3-matic, a complementary meshing software in MIMICS. The artery blocked due to stenosis was reconstructed using similar medical software, 3D Slicer, and was later refined using Meshmixer. ANSYS Fluent, one of the leading engineering simulation software, was used for this analysis. The conclusions have been drawn by monitoring wall shear stress on the artery under two different non-newtonian viscosity models. A maximum Wall Shear Stress (WSS) of 17 Pa has been recorded for the healthy carotid artery whereas the stenosed carotid artery recorded a maximum WSS of 136 Pa. Further analysis is conducted on the topology of the carotid artery based on the concentration of wall shear stress within the artery.