A process for the preparation of valgancyclovir which comprises: a) reacting a compound of formula 7, in an aprotic solvent, in the presence of a condensing agent, with a compound of formula 8, wherein R1, and R2 may be, each independently, hydrogen, an halogen atom or an hydroxyl group; the double bond may either be in the E or Z configuration or a mixture thereof to yield a compound of formula 9 b) mild hydrolysis of compound obtained in a) to give valgancyclovir.