The production of phenylethanoid glycosides (PeG) was enhanced by feeding precursors L-phenylalanine, L-tyrosine, sodium acetate and phenylacetic acid at appropriate concentrations to cell cultures of Cistanche deserticola. The optimal precursor was phenylalanine and the suitable feeding time was on the eighth day of the cell culture. Feeding 0.2 mmol l(-1) phenylalanine on the eighth day resulted in the highest production of phenylethanoid glycosides (1.10 g l(-1)), which was 75% higher than that obtained in the cell culture without precursors. (c) 2005 Elsevier Ltd. All rights reserved.