A detailed analysis of noncovalent interactions in the RNase A molecule was carried out. For this purpose, contact maps based on structural data were constructed. Three hydrophobic nuclei and five microclusters were identified, and their quantitative parameters were calculated. The contacts between amino acid residues of the active center and the hydrophobic nuclei were established. The distribution of the charged amino acid residues on the of RNase A surface was shown. The data obtained was discussed in the context of the ribonuclease A family. The substitutions seen from the alignment of amino acid sequences in the family might have influence on the spatial structure of different parts of RNase A and their mutual orientation and, consequently on the biological activity of family members.