Aspirin interacts in vitro with human low-density lipoprotein (LDL), which results in a decrease in free amino groups of apolipoprotein B and an increase of electrophoretic mobility of the particle. The aspirin-treated LDL was less efficiently recognized than native LDL by the apo B/E receptor of fibroblasts. These results suggest that aspirin in long-term treatment could influence the LDL-receptor pathway. However, aspirin-treated LDL did not bind to the scavenger receptor of macrophages.