The effects of an ayurvedic compound (MAK-5) alone or together with nerve growth factor (NGF) on the neurite outgrowth of PC12 cells was studied. PC12 cells treated with NGF alone showed a clear neurite outgrowth with a decrease of the proliferation at the dose higher than 5 ng/ml. MAK-5 alone does not induce significant neurite outgrowth in the PC12 cells and does not decrease the proliferation. The PC12 cells treated with NGF supplemented with MAK-5 showed a well-evident morphological differentiation also at low doses of NGF (less than 5 ng/ml), however, the proliferation does not decrease. We suggest that MAK-5 could contain some differentiating agents that are able to potentiate NGF inducing neuronal differentiation in PC12 cells without decreasing the cell proliferation.