The metabolism and metabolic effects of succinic acid methyl esters were examined in both NG108-15 mouse neuroblastoma x rat glioma hybrid cells and normal rat brain cells. The conversion of the dimethyl ester of 14C-labeled succinic acid (10 mM) to 14CO2 only represented 5% or less of that found at an equimolar concentration of D-[U- 14C]glucose. Neither the monomethyl nor the dimethyl ester of succinic acid exerted any significant effect upon the metabolism of D-glucose. Likewise, D-glucose (10 mM) failed to significantly affect the oxidation of the dimethyl ester of either [1,4- 14C]succinic acid or [2,3- 14C]succinic acid. It is concluded that, at variance with the situation recently documented in rat pancreatic islets and hepatocytes, the methyl esters of succinic acid are poorly metabolized in neural cells.