This study was performed to investigate the toxic effect of pyrrolizidine alkaloids from symphytum officinale i n rat. For this experiment, 120 male and female rats of Sprague-Dawley strain were used. The experimental groups were divided into five: Group CM and CF served as normal control with its gender. Group EM1 and EF1 were fed a 1% Symphytum officinal extract diet for 8 weeks. Group EM2 and EF2 fed a diet containing 2% extract diet. 4% extract diet into group EM3 and EF3 and 8% extract diet into group EM4 and EF4 were given. The results were as follows: 1. The major alkaloids of Symphytum officinale extract were symphytine, echmidine, and lasiocarpine. The amounts of total alkaloid were 168 $mu extrm{g}$ PAs/$mell$ extract. And contents of Pas in leaves were 0.05% wt.. 2. Total serum bilirubin concentrations increased significantly in group EM2, EM3, and EM4. Group EF1, EF2, EF3, and EF4 showed statistical significance for the group CF (p<0.05). 3. Aspartate transaminase activities were increased significantly in group EM3 and EM4 (p<0.05). Aspartate transaminase activities of EF1, EF2, EF3, and EF4 showed statistical significance for the group CF (p<0.05). 4. Alanine transaminase activities increased significantly in group EM3, EM4 (p<0.05). Alanine transaminase activities of EF1, EF2, EF3, and EF4 showed statistical significance for the group CF (p<0.05). 5. Alkaline phosphatase activities increased significantly in group EM2, EM3, and EM4 (p<0.05). Alkaline phosphatase activities of EF1, FE@, EF3, and EF4 showed statistical sigmificance for the group CF (p<0.05). 6. istopathological analysis of liver specimens from group EM3 and EM4 showed focal necrosis, periportal necrosis and apoptpsis. Hepatocytes obtained from group EM2 showed fatty change and hydropic degeneration in group EM3 and EM4. Chromatolysis and chromatin margination was shown in group EF2 and EF3. With the above results, it was demonstrated that the Symphytum officinal extract could induce functional change of liver, and histopathological change of liver in rats fed a diet containing extract. In conclusion, because of the risk of intoxication or adverse effect, the composition, dosage and mode of administration of herbal products should be monitored strictly. And this study serves as a reminder that herbal as well as orthodox medications may have serious side effects.