It is revealed, that the activity of neuropeptide metabolism enzymes (carboxypeptidase H, phenylmethylsulfonilfluorid-inhibited carboxypeptidase) in the female rat tissues depends upon the stage of estrus cycle. The carboxypeptidase H activity in the pituitary gland is the highest in proestrus; it is almost 3 times higher in comparison with diestrus; it is a little bit higher in striatum on the stage of estrus, than in diestrus and proestrus, in adrenals on the stage of proestrus and estrus it is a little bit lower, than in diestrus; in the ovaries on the stage of proestrus it is much higher, than in estrus and diestrus. The activity of PMSF-inhibited carboxypeptidase in ovaries on the stage of proestrus and diestrus is 1.7-1.8 times higher, than at the stage of diestrus. The activity of carboxypeptidase M in adrenal tissue at the stage of proestrus is 35-40% of that at the stage of diestrus and estrus. The activity of carboxypeptidase M in the ovaries at the stage of diestrus is 45-50% of that at the stage of diestrus and estrus. The role of the investigated enzymes in cyclic changes of a level of biologically active peptides and in regulation of estrus cycle is discussed.