Dihydrolipoamide dehydrogenase (DLD) deficiency is a rare cause of primary lactic acidosis in infancy.This article presents the results of biochemical and molecular analyses and metabolic response to treatment procedures in a 10-week old boy presenting with vomiting, progressive hypotonia, lactic acidosis (pH 7.04; BE - 20; B-lactate 6.6 mmol/l, controls Lys, breaks down the possible interaction of glutamic acid with neighboring lysine and causes electrostatic and steric repulsion, which is likely to destabilize structure in this part of the protein. In case of the A1081G mutation, resulting in substitution of Met 361 > Val, no important intermolecular interactions are broken and the reason for destabilization of the protein is not as clear.The prognosis for children with DLD deficiency is unfavorable, although long-term normalization of most metabolites in body fluids may be achieved with the proper diet and the administration of sodium dichloroacetate.