Summary ― Hepatic and plasma lipid changes were investigated in hybrid ducks after steatosis was induced by overfeeding. Fourteen hybrid ducks were force-fed (11 kg corn in 13 days). The liver of the overfed ducks weighed ten times more than that of controls (695 vs 69 g). The phospholipid, ash, water and protein content of the liver were only slightly higher (2.6-, 3.6-, 4.4-and 3.2-fold, respectively) but the liver lipid concentration was 16.5 times higher after than before overfeeding (56.1 vs 3.4 g/100 g liver, respectively). Liver phosphatidylcholine concentration was higher in the control group (32.4 vs 22.9 mol/100 mol phospholipid) revealing a choline deficiency that could contribute to the development of liver steatosis. In liver phospholipid, the level of linoleic and arachidonic acids were markedly decreased in the overfed ducks, from 5 and 18.1 to 3.7 and 7.1 mol/100 mol fatty acids, respectively, and were mainly replaced by oleic acid. Plasma triacylglycerols increased 5.9-fold, cholesterol 2.2-fold and phospholipids 1.6-fold. Heat-induced (50 min at 105 °C) fat release, an index of poor liver integrity, was particularly high for the large, fat livers which contained low levels of phospholipids and phosphatidylcholine.