The biotransformation of (RS)-1-phenylethanol with cultured cells of Catharanthus roseus gave its vicianoside [α-L-arabinopyranosyl-(1-6)-β-D-glucopyranoside], primeveroside [β-D-xylopyranosyl-(1-6)-β-D-glucopyranoside] and gentiobioside [β-D-glucopyranosyl-(1-6)-β-D-glucopyranoside] via the corresponding glucoside. It was found that primeveroside and gentiobioside were enantioselectively composed of only (R)-1-phenylethanol as its aglycone moiety.