The invention concerns diamines of general formula (I), wherein: A represents a group A1 or A2 of general formula (II); B represents a group B1 or B2 of general formula (III); X represents a SO.sub.2, CH.sub.2, C.dbd.O or COO; YZ represents a group of formula CH(R25)--CH(R26) or CH(R27).dbd.(R28), and R1 to R28, identical or different, represent independently of one another, a hydrogen or halogen atom or an alkyl, cycloalkyl, CN, NO.sub.2, hydroxy, aryl, aralkyl, alkoxy, aryloxy, amino, alkylamino, dialkylamino, cycloalkylamino, arylamino, arylalkylamino, diarylamino diarylalkylamino, trihalogenoalkyl or trihalogenoalkoxy group, provided that in the group A1, at least one of the radicals R1, R2, R3, R4 or R5 represents the hydrogen atom when the other four do not represent the hydrogen atom and in the group B1, at least one of the radicals R13, R14, R15, R16 or R17 represents the hydrogen atom when the other four do not represent the hydrogen atom, and their salts with a pharmaceutically acceptable acid, in the form of racemic mixture or their optically pore isomers. The invention also concerns their preparation, pharmaceutical compositions comprising them and their use as CaSR activity modulator and as medicine particularly designed for the treatment of psychological diseases and disorders involving CaSR activity modulation.