It is known that extracts of cryopreserved organ fragments of pigs and piglets stimulate the processes of reparative regeneration. Therefore, the study of the extracts is essential for understanding the mechanism of their biological effects. In this paper was studied the molecular mass distribution of peptides in the extracts of cryopreserved heart fragments of pigs' and piglets', i.e., the chromatograms of pigs' heart extracts show 3 picks, whilst piglets' heart extract show 6 picks. The peculiarity of pigs' heart extracts is the absence of peptides with molecular mass of 10,000 and more. The differences in the intensity of extracts fluorescence prove that the peptides in pigs' heart extracts contain greater amount of tryptophan residues accessible for solvent. The synchronous fluorescence spectra of extracts were obtained which allows the identification of extract without assessment of their components. Results shown in this research could be used for control and standardization of heart extracts peptide composition under investigation of their biological quality.