Scutellariae baicalensis GEORGt Acorus gramineus SOLAND and Gastrodia elata BLUME are traditional medicines used in the treatment of incipient stoke. In this study we investigated their effects on various aspects of neuronal differentiation in single or composite forms. Water-extracts of these medicines showed neuroprotective effects on cultured rat cortical neurons in normoxia and hypoxia. To understand the mechanism for neuroprotection we carried out various cell biological assays. They stimulated initial differentiation of neuronal development (transition from stage 1 to 2), and increased the number of spines and the length and number of dendritic processes. These effects were best manifested in the experimental group, which were given a mixture of the three kinds of extracts (p<0.01). To assess improvement of brain functions we carried out Morris water-maze tests for the mice that were fed on these extracts instead of water for 4 weeks. The experimental groups, especially those which were given the mixture of the three kinds of extract, showed significant (p<0.01) enhancement in memory as early as one day after the learning trial. These results indicate that these three kinds of extracts have synergistic effects on neuronal protection and improvement of brain functions.