OBJECTIVE: To study comparatively the characteristics of absorption and distribution of mercury and arsenic from realgar and cinnabar of Angong Niuhuang Pill in normal rats and the rats with cerebral ischemia after oral administration. METHOD: The blood samples and homogenates of liver, kidney and brain were prepared at various intervals after the animals were treated with Angong Niuhuang pill ig. The levels of total mercury and total arsenic in the blood and the organ homogenates were measured with Microwava Accelerated Reaction System and AAs, respectively. RESULT: The blood concentrations of mercury and arseic reached the highest point in normal rats at one hour following single oral dosing of Angong Niuhuang pill. In normal rats, the mercury distribution was characterized by its higher level in blood and kidneys than in other organs, while a higher distribution of arsenic was found in blood than in organs. No difference in the distribution of mercury or arsenic was found between normal rats and rats with cerebral ischemia after the treatment with the pill. CONCLUSION: The highest level of mercury or arsenic in blood occurs at one hour after oral administration of the pill in normal rats. There is a higher distribution of mercury in blood and kidneys, while a higher distribution of the arsenic only in blood. There is no significant difference in the distribution of mercury or arsenic between the normal rats and the ischemic rats.