Livers of turkeys fed low and high glucosinolate rapeseed meal diets for 16 weeks were examined ultrastructurally. Hepatocytes from birds fed on Tower rapeseed meal (0.15 mg of glucosinolate per g) showed a mild accumulation of lipid droplets and an apparent increase in lysosomes and microbodies. The parenchymal cells of the livers of turkeys fed on Target Rapeseed meal (9.50 mg of glucosinolate per g) exhibited varying degrees of degenerative change: dilation of endoplasmic reticulum, swelling of mitochondria with fragmentation and loss of cristae, presence of autophagic vacuoles, myelinoid bodies, electron-dense lipidlike droplets, vesiculation of cytoplasm and necrosis of the hepatocytes. The electron-dense lipidlike bodies were most frequent at the biliary pole. Sinusoids near the degenerating hepatocytes were often disrupted and perisinusoidal mesenchymal cells in the area showed distended cisternae of granular endoplasmic reticulum. Such cells or fat-storing cells were frequently seen in the vicinity of proliferated collagen fibrils and degenerating hepatocytes. These observations suggest that degenerative alterations of hepatocytes accompanied or preceded the development of fibrosis in turkeys fed rapeseed meal high in glucosinolate.