CoA (0.1 M) induced an increase in oxygen uptake and carbon dioxide production from acetate-I-C¹⁴ in cultures of liver cells from chicken embryo. The concentration of CoA adequate to produce these effects is far larger than the previous used to stimulate lipid synthesis in liver slices free of CoA. Perhaps growing liver cells of chiken may be more resistant to be permeated by exogenous CoA, than the rat liver slices, and (or) CoA in higher concentration, as used in the present study, may induce a pharmacodynamic effect rather than a coenzyme function. Moreover, in both the previous and the present experiment “exogenous” CoA produced a remarkable effect on the metabolism of liver tissue.