Objectives : The purpose of this investigation is to evaluate the effects of Woohwangcheongsim-won (WC) on the in vitro neuronal development and alteration in gene expression in a hypoxia model using cultured rat cortical cells. Methods : E₁₈ rat cortical cells were grown in a neurobasal medium containing B27 supplement and various concentration of WC. Initial development of growth cone was investigated by phase-contrast microscopy, while dendritic spine formation and synaptogenesis were investigated by immunocytochemistry with SynGAPα(a postsynaptic marker) and synaptophysin (presynaptic marker) antibodies. Alteration in gene expression was analyses by microarray using rat 5K-TwinChips. Results : WC suppressed the development of growth cones and WC increased the number of dendritic spines at 20 and 50㎍/mL concentration but there was no statistical significance. Instead, it significantly decreased the number at 100㎍/mL. The expression of anti-apoptosis gene Bcl2-like 1 (Bcl211) increased (Global M=0.46), while Akt1 decreased. Proapoptosis genes Bad and PDCD2 increased. The expression of hemoglobin alpha 1 (probably neuroglobin) increased (Global M=0.93). The expression of antioxidants such as catalase, heme oxygenase (HO), and PRKAG2 gene increased. The expression PKC gene increased. The expression of retinoic acid receptor alpha (RARα) increased significantly (Global M=1.0). Conclusions : These data suggest that WC trends to suppress cellular activity slightly in normoxia and increases the expression of apoptosis-, antioxidation-, oxygen capture-related genes in hypoxia, but increases Bcl111 that anti-apoptosis gene, on the other hand increases Bad, PDCD2 that pro-apoptosis genes, too..