This experiment continued from Report I was conducted to examine the breakdown of cysteine and methionine by the resting cells of some strains of Sh. flexneri, and the following results were obtained. 1. When cysteine or methionine is added independently to the suspension of these resting cells, the breakdown of these amino acids does not occur, but when added with glucose it is analyzed: in the case of cysteine desulfydration occurs, H(2)S is formed and deamination can be observed, and in the case of methionine dethiomethylation occurs, CH(3)S-SCH(3) or relating compound is formed and deamination can be also observed. 2. Such breakdown of cysteine and methionine is accelerated by VB(6). 3. Compared with the ability of analysis of these S-containing amino acids of each strain, cysteine is more analyzed than methionine by the suitable cells as S source and methionine is more analyzed by the suitable cells as S source.