Liver haemorrhage was studied in laying fowl given diets containing rapeseed meals prepared from seed of varieties of Brassica napus grown in the United Kingdom and from seed of the varieties Tower and Erglu. There was lower mortality from liver haemorrhage in birds given Tower than in those given B napus (UK) meal but haemorrhagic lesions in the liver occurred in all groups of birds given rapeseed meal diets, whichever meal was included. Histological and electron microscopical examination revealed several abnormalities in the structure of the hepatocytes. Early degenerative changes were, enlargement of the intercellular spaces, swelling of the mitochondria, distortion of the rough endoplasmic reticulum profiles, disruption of the hepatic sinusoids, and in the most severely affected areas there were necrotic hepatocytes. These abnormalities were observed in sections from the livers of two hybrid strains of birds given the B napus (UK) or Tower rapeseed meal for four weeks or longer.