Sitosterolemia is a rare inherited disease in which plant-derived sterols (sitosterol) accumulate in the body and lead to premature atherosclerotic plaques. The disease is caused by mutations in either of two ATP-binding cassette (ABC) half-transporters, ABCG5 or ABCG8, but the exact role of these genes in the trafficking of sterols has been unclear. In November 18 early edition of Proceedings of the National Academy of Sciences, Liqing Yu and colleagues at the University of Texas Southwestern Medical Center at Dallas, USA, show that ABCG5 and ABCG8 are the major hepatobiliary transporter of both dietary and endogenously synthesized neutral sterols (PNAS, cgi/doi/10.1073/pnas.252582399, November 18, 2002).