The thickened gallbladder walls (GBWs) are often ultrasonographically seen in patients with severe liver damages such as acute hepatitis and liver cirrhosis. However, causal factors of ultrasonographic GBW thickening have not been known well at present. In order to investigate the mechanism of the GBW thickening in liver diseases, the changes of the GBW in guinea pigs poisoned with D-Galactosamine (GalN), as one type of the models with acute hepatic injury, were studied histologically and ultrasonographically. The markedly thickened GBWs were observed in the GalN administered group as compared with the control group. The dilated lymph vessels and subserosal edema were seen in the thickened GBWs as well. In the GBWs the marked lymphangiectasia illustrated with the help of Indian ink injected into the liver beds were seen in the GalN administered group, while there was no any detectable inflammatory findings in the thickened GBWs. From these facts, it has been suggested that in severe hepatic injury the overproduced lymph plasm from the liver reached the lymph vessels in the GBWs and subsequently the lymph plasm overflowed to cause subserosal edema and dilatation of the lymph vessels in the GBWs. It is supposed, therefore, that the process stated above is one of the main causal factors of the GBW thickening in acute hepatic injury.