Atomic absorption spectrophotometric method, for determination of arsenic and iron concentration in finger and foot muscles from Blackfoot Dim Patients(BFDPs), by amputation were developed. Thirty-four cases of BFDPs, at the most strict clinical examination and thirty cases of Non-BFDPs(NBFDPs) from the traffic accidents. NBFDPs from the same district were compared as the controls. Arsenic has been claimed to be major causative agents of Blackfoot Disease(BFD) in the south-western coast of Taiwan. We published several papers on this and presented a conception that, as with the increase in clinical stages from the zero, first, second, third and fourth, the increase in the arsenic concentration in blood, hair and urine accompanies as the BFD progressed, although at the third and fourth stages, arsenic decrease might be induced by the antagonistic effect of selenium, zinc and iron. For the purpose to prove this, the study was carried out to check whether at the fourth stage, the concentration of arsenic in BFDPs finger and foot muscles by amputation are higher than that of NBFDPs and whether it is also the case with the blood of BFDPs . The arsenic in muscles of finger and foot of BFDPs by amputation was more than 10 times higher than the NBFDPs at the raze of 0.80±0.57 ug/g > 0.07±0.05 pglg and they were also about 8 times higher than the blood of BFDPs at the fourth clinical stages at the rate of 0.80±0.57 pg/g > 0.091±0.052 pg/ml. Both of them had significantly difference with P<0.01. These evidences directly indicated that arsenic might be a major causative agent of BFD. The iron in muscles of finger and foot of BFDPs by amputation were also about 2 times higher than that of NBFDPs at the rate of 39.63±23.54 µg/g > 19.82±7.61 µg/g and had a significance difference with P<0.05. These results were on the contraiy to the blood, when compared with the blood iron concentration in BFDPs at fourth stage and NBFDPs. The NBFDPs were higher than the BFDPs at the rate of 553.28±92.96 µg/ml > 510.71±163.52 pg/ml. Therefore iron may have some antagonistic effect to arsenic toxicity for the BFDPs and this fact is worthy of more academic study of the BFD in clinical application.