Resveratrol is a plant-derived phenol but the mechanism that regulates its biosynthesis remains unidentified. Stilbene synthase (STS) catalyzes resveratrol formation in vivo and we have proposed that inducers of resveratrol production affect STS expression through an unidentified epigenetic mechanism. To investigate the role of DNA methylation in resveratrol biosynthesis, we treated both rolB transgenic and empty vector control Vitis amurensis cell cultures with the DNA demethylation agent, 5-azacytidine. Treated cells had increased resveratrol production through activation of VaSTS10 expression. The lowest levels of cytosine methylation were at the 5'- and 3'-ends of the VaSTS1 protein-coding sequence. Cytosine methylation decreased mostly at the 5'- and 3'-ends of VaSTS10 after azaC treatment with an intriguing regularity in the number of cytosine nucleotides within the 5'- and 3'- ends of the protein-coding sequences. Thus, cytosine methylation is crucial for the regulation of the resveratrol biosynthetic pathway.