[en] The effect of multiple strain aging on the relationships between yield strain Esub(L), strain rate V and yield front propagation rate Usub(L) has been experimentally investigated. It is shown that multiple strain aging increases the internal resistance to plastic flow by some limited value which is little dependent on V; when the ultimate hardening is achieved the material becomes plastically unstable. The results have been considered in connection with the conceptions of the dislocation substructure of the solid solution b.c.c. under multiple strain hardening as exemplified by armco iron