This invention relates to a process for preparing intermediates useful in preparing Valsartan and to a process for preparing the latter, together with synthesis intermediates of formula (IV), (V) and (VI), useful for manufacturing a medicament for the treatment of arterial hypertension or heart failure. The process for preparing Valsartan permits it to be prepared on an industrial scale with high yields and without racemisation problems, in addition to using simple and available starting products. The invention also provides a process for preparing the intermediate of formula (VI), from an intermediate of formula (V) that does not require protection of the carboxylic acid prior to N-acylation.