In the above-mentioned paper [Journal of Process Control 11 (2001) 69-80], the problem of approximate output regulation of a class of nonlinear systems was considered. By a step-by-step systematic design procedure, a nonlinear controller is designed which is a dynamic and state feedback. However, we find that there exist some mistakes in the proof of the main theorem of this paper. This note points out the flaw of the commented paper. (c) 2007 Elsevier Ltd. All rights reserved.