Two differently salt-sensitive wheat genotypes were imbibed in 0·4 M NaCl for 72 h or, alternatively, for 48 h and then transferred to water. Seed germination, fresh weight and protein synthesis in embryos were determined. The following differences were found in the synthesis of in vivo [ 35 S]methionine-labelled proteins during salt imbibition: ( a ) a general decrease or disappearance of polypeptides specific to the radicle emergence phase in the salt-sensitive genotype; ( b ) a new synthesis of polypeptides which are not found during water imbibition and are common to both genotypes; ( c ) a differential synthesis of polypeptides that are unique to each cultivar. Upon return to water, salt-induced proteins ceased to be synthesized while proteins associated with an advanced germination phase were actively produced. These results suggest that the expression of 'salt stress' proteins is related to the adaptation process of seeds to salinity as well as to the genetic constitution of a selected salt-tolerant genotype. Copyright 1993, 1999 Academic Press