THE brief report by Reid1 of the “production of clear-cut deficiencies of … choline …” in the guinea pig is of considerable interest, as Handler2 had previously failed to produce fatty livers in guinea pigs maintained on a hypolipotropic diet and had correlated this failure with the low choline oxidase content of guinea pig liver8. In view of this discrepancy, we present histochemical evidence here of the centrilobular deposition of fat in the livers of guinea pigs fed a hypolipotropic diet. Such accumulation of fat is characteristic of choline deficiency in the rat4.