This interesting work, easy to apply, is founded on elementary results of linear algebra, and turns on robust pole assignement, by feedback, in linear time invariant multivariable systems, subject to structured perturbations. When zero or unitary block in the transition matrix are structural, it is necessary to select feedback gains to ensure that the prescribed closed loop poles are insensitive to restricted perturbations. To resolve the problem, the authors establish a global measure of the robustness of the poles to perturbations having a given structure. A computational method and examples of application are given for minimizing this global measure of pole sensitivity to a given class of perturbations. The authors expect that the described procedures are extendable, for example, to robust pole placement by output feedback.