SH medical compounds used in this study were BAL, sodium thiosulfate, cystine, menthionine and sodium mercaptoacetate. 1. In the animal tests on the effectiveness of SH medical compounds, BAL was the most effective and then sodium thiosulfate was next, while scarecely effect was observed in the experiments of cystine, methionine and sodium mercaptoacetate. 2. By the administration of PAM, SH enzyme such as mucoprotein was promptly and certainly reactivated as well as cholinesterase.