Crotonaldehyde is a common environmental pollutant, formed upon combustion of fossil fuels and wood. Inhalation of tobbacco smoke is also a significant source of crotonaldehyde. Crotonaldehyde exhibits many toxicological properties, including an ability to cause multi-organ toxicity in laboratory animals; DNA damage and mutagenicity in vitro; and carcinogenicity in vivo. As a reactive bifunctional electrophile, crotonaldehyde readily generates adducts in a range of cell macromolecules. Crotonaldehyde human serum albumin(HAS) conjugate was fully characterized, and has been used for developing crotonaldehyde-quantifying assays.