Background: The efflux of cellular cholesterol mediated by apolipoprotein (apo)A-I and ATP-binding cassette transporter A1 (ABCA1) is a major pathway of reverse cholesterol transport. We investigated the effect of aspirin on this process. Methods: The expression levels of ABCA1 in RAW264.7 cells were determined using reverse transcription polymerase chain reaction and Western blot analysis. 3H-cholesterol efflux was measured by scintillation counting. Results: 0.5 mmol/l aspirin increased apoA-I-mediated cholesterol efflux and increased the expression of ABCA1. By increasing the dose of aspirin higher than 0.5 mmol/l, ABCA1 expression and function were significantly decreased. In cells transfected with a specific peroxisome proliferator-activated receptor (PPAR)-α small interfering RNA, the induction of ABCA1 expression and apoA-I-mediated 3H-cholesterol efflux by aspirin were substantially suppressed. Conclusions: The data demonstrate that low-dose aspirin increases ABCA1 expression via a PPAR-α-dependent mechanism and increases apoA-I-mediated cholesterol efflux.