Plasma taken from hepatic failure rats induced by D-galactosamine was used to observe the variatiation in its chromatogram obtained by conducting a high performance gel-chromatography (TSK G2000SW used). The progress of hepatic failure caused distinct increase in the 12 abnormal peaks, especially peak b contained middle molecular weight substances, which showed a good correlation with the condition of progressing hepatic failure. Thus, the measurement of variation in gel-chromatogram, especially, in peak b, is effectives as a parameter of hepatic failure in progress.