It was attempted to observe the antidotic effects of garlic on mercury intoxicated rat model in vivo. The experimental model group consists of garlic juice treated group (G), garlic juice-mercury treated group(MG), mercury treated group (M), and control group (basal diet), The garlic juice of 2% to the daily diet by weight was administered orally to G and MG groups, The single dose of 2.5mgHG/Kg per week was given orally to M and MG groups. the study was carried out for 4 weeks. The results of experiment were as follows. For the group of Mg, and the weight increasing rate was improved to about 30% compared to that of group M. Furthermore a general tonic efficay of garlic was observed in G group in term of increased weight gain rate (bout 15%) than control. In the biochemical studies of rat blood garlic showed effects on lowering the abnormally elevated GPT, GOT, uric acid creatinine value, and especially in lowering the BUN value of Hg treated rat that was selectively elevated in the case of impared renal function such as acute gromerulonephritis caused by Hg intoxication. In the analytical studies blood and renal Hg contents. HG group showed lower value (0.3, 0.33ppm) than that of M group (0.46, 0.51 ppm) Significant difference in reducing Hg level due to the antidotic effect of garlic was observed. In conclusion, it was revealed out from this research, the main principles of garlic, nonprotein sulfur amino acid (alliin) and sulfur compounds (allicin and diallyl disulfides) seem to almost certainly have an antidotic effect on mercury intoxication of rat in vivo.