Atherosclerosis causes heart attack and stroke and is a major fatal disease in the Western world. The formation of atherosclerotic plaques in the artery walls is the result of LDL particle uptake, and consequently of cholesterol accumulation in macrophage cells. Excess cholesterol accumulation eventually results in cholesterol crystal deposition, the hallmark of mature atheromas. We study the formation of cholesterol monohydrate crystal polymorphs on lipid bilayer membranes and in cells enriched with cholesterol. This work may provide information on the crystal growth mechanisms involved, once the factors that favor the formation of different structures are understood