Vanillin is one of the most widely used flavor compounds in food and personal products. It has been reported that vanillin is able to inhibit mutagenesis induced by chemical and physical mutagens, and to suppress the invasion and migration of cancer cells. Herein we used the oligonucleotide microarray approach to study gene expression profile of vanillin-treated human hepatocarcinoma cells. Microarray data followed by gene ontology (GO) investigation displayed that vanillin-affected clusters of genes involved in cell cycle and apoptosis. Genes down-regulated by vanillin were grouped into three GO categories, regulation of cellular process, cell cycle, and death. Furthermore, most of the down-regulated genes were associated with cancer progression. Knowledge-based analysis further indicated that Fos may play a central role in the regulation of gene expression network. Analysis of Fos-related transcription factor, activator protein 1 (AP-1), showed that vanillin inhibited AP-1 activity in a dose-dependent manner. Furthermore, the phosphorylation of extracellular signal-regulated protein kinase (ERK) was diminished with increasing concentrations of vanillin, indicating that vanillin-regulated AP-1 activity via ERK pathway. In conclusion, our data suggested that vanillin exhibited the anticancer potential by the regulations of cell cycle and apoptosis. Moreover, its regulation may involve the suppression of a central molecule, AP-1.