We had previously used an electrophoretic transfer procedure to determine the topographic distribution of low density lipoprotein (LDL) accumulation in the aortic intima of normolipemic swine. In this present study we have employed a similar procedure to assess whether LDL-rich sites consistently demonstrate increased intimal thickening at the iliac bifurcation and common iliac arteries. The topographic distribution of LDL-rich sites was determined in the aortas of six subjects ranging in age from 16 to 36 years, by transferring LDL by electrophoresis from the tissue into an agarose gel containing anti-LDL, and then staining the immunofixed LDL in the gel for lipid. LDL-rich sites were found in all but two of these cases. On the basis of control studies establishing the level of nonspecific staining, we determined that the cutoff between LDL-rich and LDL-poor zones was 37 mg apoB protein/mm2 intimal surface area. Intimal thickening was found to be threefold greater in LDL-rich than in LDL-poor regions. These results confirm and extend earlier immunohistochemical studies suggesting a preferential accumulation of LDL at sites of intimal thickening in human arteries.