A finite element model of the human carotid bifurcation was developed to investigate the possibility that pressure-induced arterial wall stresses lead to the formation of atherosclerosis. The effect of material non-homogeneity was investigated by measuring the distribution of collagen and elastin in cadaver specimens and applying different material constants where appropriate. Both the homogeneous and non-homogeneous models included the residual stresses. The histology results revealed that the outer wall of the apex contained proportionally more collagen. Elsewhere, relative distributions of collagen and elastin were uniform through the thickness. The finite element model results demonstrated that the area of highest stress concentration was the lateral wall of the carotid sinus. The outer wall stress at the apex was higher for the non-homogeneous model owing to the higher collagen content there, but the stresses elsewhere in the model were relatively unaffected. A statistical comparison of the stress distribution to previously published data on intimal thickness showed that areas with a high ratio of inner to outer wall stress coincided with greatest intimal thickening (r = 0.800, P < 0.00005). The inclusion of material non-homogeneity had little effect on this correlation.