Atherosclerosis is a circulatory system disease characterized by the accumulation of cholesterol, calcium, complex carbohydrates, blood and cellular remnants, and fibrous tissue in the intimal layer of the artery. The deposition of these particles at the arterial wall may result in a stenosis, a decrease in the diameter of the artery. The focus of the present paper is to investigate the effect of the stenosis on the transport of the low-density lipoprotein, or LDL, from the bloodstream to the arterial wall. This analysis models the hydrodynamics of the artery using lubrication theory. This method yields a Poiseuille type of velocity profile, with a modification due to the changing vessel diameter. Mass transfer of LDL particles to the wall of the artery is considered using the species continuity equation for dilute solutions. A pseudo-steady-state model is developed since the radius of the artery is assumed to decrease much more slowly with time than the rate required for the establishment of concentration profiles in the solution. Convective transport in the radial and axial directions couples the hydrodynamics to the species balance equation. Diffusion in the axial and radial directions is also considered. The effect of varying convective, reactive, and geometrical parameters is analyzed. A first approximation, which assumed negligible radial convective contributions to mass transport, yielded quite different results compared to cases where this term was included. Thus, from the analysis, it appears that the convective transport in the radial direction is very important when considering mass transport in a channel of changing diameter, even when the relative change is small.