Changes in the fatty acid compositions of liver subcellular particles in pyridoxine-deficient rats were investigated in the following three fractions : 1) Mitochondria : The total fat of the pyridoxine-deficient group tended to show a lower proportion of arachidonate, whereas in the phospholipid fraction, the percentage of linoleate was higher and that of arachidonate was lower in the pyridoxine-deficient group than in the pair-fed control. 2) Microsome : It was elucidated that the pyridoxine-deficient animals indicated significantly higher proportion of linoleic acid and significantly lower proportion of arachidonic acid on comparison of the total fat. In the phospholipid fraction, these changes were more strongly manifested. 3) Supernatant : In the supernatant fraction, no significant differences were found between the proportions of the fatty acids in the pyridoxine deficient and the control animals. (Received Jan. 13,1971)