Terpenoids represent one of the major classes of natural products and serve different biological functions. In grapes (Vitis vinifera) a large fraction of these compounds is present as non-volatile terpene glycosides. We have extracted putative glycosyltransferase (GT) sequences from the V. vinifera genome database that show similarity to Arabidopsis thaliana GTs whose encoded proteins glucosylate a diversity of terpenes. Spatial and temporal expression levels of the potential VvGT (Vitis vinifera glycosyltransferase) genes were determined in five different grapevine varieties. Heterologous expression and biochemical assays of candidate genes led to the identification of a UDP-glucose:monoterpenol β-D-glucosyltransferase (VvGT7). The VvGT7 gene was expressed in various tissues in accordance with monoterpenyl glucoside accumulation in V. vinifera cultivars. Twelve allelic VvGT7 genes were isolated from five cultivars and their encoded proteins biochemically analyzed. They varied in substrate preference and catalytic activity. Three amino acids, which corresponded to none of the determinants previously identified for other plant GTs were found to be important for enzymatic catalysis. Site specific mutagenesis along with the analysis of allelic proteins also revealed amino acids that impact catalytic activity and substrate tolerance. The results demonstrate that VvGT7 may contribute to the production of geranyl and neryl glucoside during grape ripening.