Chaos-theoretical analysis is made on possible candidates for the structural quantities. Since this is a first attempt to incorporate chaos into protein structural studies, a brief introduction to chaos especially the correlation integral method is given. It is shown that for several globular proteins the quantities called N14 and the distance rho of each C alpha atom from the center of mass suggest their deterministic origin which, we consider, is an essential requirement for a parameter to be recognized as the structural quantity. The claim made by the originator of N14 that the quantities N14 and rho can be good candidates for structural quantities is supported here by a completely new and different analysis.