The purpose of this work is the study of the “response positiveness” properties of multi-variable non-minimum phase systems subject to output inequality constraints. In previous work the authors have introduced the notion of positive response systems and their behaviour was studied in the SISO case under output constraints. The present paper shows the MIMO case systems and discusses upon the conservation of the mentioned property linked to the number of active output constraints versus number of system input. It is shown by geometric approach that an over-controlled system has always a “positive response”.