Cerebrolysin is a peptide mixture with neurotrophic effects that might have the ability of both reducing amyloid burden and improving synaptic plasticity in Alzheimer's disease (AD). In order to determine if Cerebrolysin is capable of ameliorating the neurodegenerative and behavioral alterations associated with amyloid beta (A beta) production; transgenic (tg) mice expressing mutant human amyloid precursor protein (APP) under the Thy1 promoter were treated with Cerebrolysin or saline alone starting at 3 or 6 months of age for a total of three months. Animals were then tested behaviorally (at 6 and 9 months of age respectively) in the water maze and then analyzed neuropathologically for amyloid burden, synaptic density, astrogliosis and apoptosis. Performance analysis in the water maze showed that in the younger tg mice cohort, Cerebrolysin treatment significantly ameliorated the performance deficits. In the older cohort, there was a trend toward improved performance in the learning curve. Neuropathological examination showed that in both age/treatment groups, Cerebrolysin promoted synaptic regeneration, and reduced the proportion of neurons displaying DNA fragmentation by the (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method. Moreover, Cerebrolysin treatment reduced A beta burden by 43% in the young group and by 27% in the older group. Taken together, these results suggest that Cerebrolysin treatment might have beneficial effects in patients with cognitive impairment by reducing A beta accumulation and promoting the preservation of synaptic terminals.