Contaminants, such as polycyclic aromatic hydrocarbons (PAHs), can be absorbed on the particles of indoor dust, which may pose potential health risks. In this study, indoor dust samples were collected and sieved into 6 size fractions (i.e., <43 mu m, 43-63 mu m, 63-100 mu m, 100-150 mu m, 150-200 mu m, and 200-2000 mu m). Ingestion bioaccessibility of PAHs was measured by physiologically based extraction test. Bioaccessibility in fractions of 200-2000 mu m was generally higher than those in other particle sizes. Daily uptake doses based on benzo(a) pyrene toxic equivalency quantity were 1.09-15.0 ng/d/kg, and peaked at fractions of < 43 mu m, while doses considering bioaccessibility ranged from 0.02 to 0.21 ng/d/kg, and peaked at fractions with relatively larger particle size. Cell toxicity was also investigated by human normal liver cell line viability through exposure to organic extracts of indoor dust fractions with various particle sizes. Our results indicated that it is crucial to consider dust particle size and bioaccessibility during risk assessment.