Glutamate induced neurotoxicity has been proposed to account for the loss of neurons after ischemia as well as in the cause of neurodegenerative diseases. We have studied the effects of exogenous glutamate on survival of neurons from chick embryo telencephalon, precultured with a peptide derivative for 8 days. The peptide derivative Cerebrolysin is a drug produced by standardised enzymatic breakdown consisting of 80% peptides and 20% amino acids. Toxic effects of acute glutamate exposure were prevented by Cerebrolysin in a concentration-dependent manner. 20 and 40 microliters Cerebrolysin produce distinct neuroprotective effects. However, 80 microliters Cerebrolysin/ml nutrition medium more than doubles neuronal viability compared to untreated control cells. These concentration-dependent effects of Cerebrolysin were evident even at the light microscopic level.