The contents of the sulfur amino acids, and the activities of cystathionine beta-synthase and cystathionine gamma-lyase were measured in various regions of the brain and several other tissues in both normal mice and rolling mice Nagoya. The cystathionine content and cystathionine beta-synthase activity were found to be unevenly distributed in various regions of the brain in both normal mice and rolling mice Nagoya, being highest in the cerebellum. Except for the mesencephalon and thalamus plus hypothalamus, the cystathionine content and cystathionine beta-synthase activity in the brain regions of rolling mice Nagoya were much higher than those of the normal mice. The cystathionine content after D,L-propargylglycine treatment was also found to be unevenly distributed in various brain regions in both normal mice and rolling mice Nagoya. The concentrations of cystine and methionine were also higher in all regions of the brain of rolling mice Nagoya than those of normal mice, while the concentration of taurine in the various regions of the brain was almost the same in normal mice and rolling mice Nagoya. Cystathionine beta-synthase and cystathionine gamma-lyase activities in the liver, kidney, and pancreas were almost the same in both the normal mice and rolling mice Nagoya.