Four different protein families (two proteinase inhibitor families, myoglobins and lysozymes) were surveyed for correlated mutations with respect to the position distance and their significance in structure stabilization and biological activity. They were chosen for this study in order to verify the currently admitted model of mutational correlation relationship with respect to spatial contact of the residues and contribution in protein biological activity. There was observed high contribution of spatially dispersed residues (which are also not involved in the protein active center) in mutational correlation. Because of the significantly large distance between correlated positions these cases do not correspond explicitly to any mechanism included in current hypotheses. It is suggested that the role of residue spatial contact in structure preservation, intermolecular interaction and active site rescue mechanisms only partially explains the correlation phenomenon.