The comparative research of influence hypothalamyc cytokine PRP on haematomorphological parameters of blood healthy and ill of the cows is carried out. Under action the preparation differs the tendency to normalization of the unvestigated parameters. The activity influence PRP in formation immunomodulation of the protective mechanism causes decrease of number those lymphocytes, which increase promotes are further progress of process at leucosis. At the ill of the cows are found out degeneration structural frustation as less steady average and large lymphocytes and also undifferently and atypical cancerous cells, thus more reactive small lymphocytes to changes are not exposed. The essential changes haematomorphological parameters of blood at the healthy cows are not observed under action of a preparation.