Abstract: Studies addressing histological, histochemical, biochemical, endocrinological, and behavioral changes in animals and humans receiving the flavor enhancer monosodium 1-glutamate (MSG) are reviewed. Also discussed are the effects of the artificial sweetner aspartame, and the development of a whole class of neurobiological tools for basic research, the excitatory neurotoxic amino acids (e.g., kainic acid). Despite the extensive amount of work which has been carried out in the 20 years since the reports of glutamate-induced neurotoxicity, a general consensus concerning the safety of unrestricted use of MSG in foods has not yet been attained. Food industry-sponsored research has, however, confirmed the neurotoxic effects of orally-administered MSG in neonatal rodents. Further study is needed to resolve the question of MSG as a food additive. (wz)