Mutations in multidrug resistance 3 gene (MDR3 or ABCB4) underlie progressive familial intrahepatic cholestasis type 3 (PFIC3), a severe pediatric liver disease progressing to cirrhosis. Abcb4−/− mice exhibit slowly developing hepatic lesions that can be accelerated by feeding a cholic acid (CA)–supplemented diet. We investigated the beneficial effects of a soybean lecithin (L)–supplemented diet in this model of liver disease. Abcb4−/− mice and wild-type (WT) controls were divided in four groups by the diet they were fed: control (C) diet, L-supplemented diet, CA–supplemented diet, and L- and CA-supplemented (L+CA) diet. After 2 wk on these regimens, liver enzymes and bilirubin were measured in serum with bile flow, total bile acids, and cholesterol (CHOL) and phospholipid (PL) concentrations in bile. Ductular hyperplasia, portal fibroblastic cell proliferation, myofibroblast activation, and hepatic fibrosis were quantified on liver sections. Abcb4−/− mice fed the C diet exhibited mild liver damage. CA produced very high elevations of serum liver enzymes and bilirubin with significant bile duct proliferation, peribiliary fibroblast activation, and fibrosis. The L-supplemented diet dramatically mitigated the hepatic damage in CA-supplemented diet animals. We conclude that L is protective against liver disease in Abcb4−/− mice and suggest that it could offer potential benefit in PFIC3.