A B S T R A C T R I~ S U M I~After defining and describing the main physicochemical mechanisms governing the autogenous shrinkage of concrete, a number of different experimental approaches used to asses this phenomenon are discussed. The base principle and a detail description of a new experimental technique aiming to completely characterise the autogenous shrinkage of a cement paste are presented. The originality of the technique comes from the fact that the variation of the external volume (external autogenous shrinkage) and the volume of the gasfilled spaces in the liquid phase after the hardening (internal autogenous shrinkage) are measured separately and simultaneously. The total autogenous shrinkage is the sum of the internal and external autogenous shrinkages. A number of experimental results are presented to demonstrate the validity of the proposed experimental approach and to analyse the effect of water/cement ratio on the development of internal and external shrinkages. Apr~s avoir ddfini et ddcrit les principaux m~canismes physico-chimiques 2~ l'origine du retrait endog~ne du bdton