The design of robust stabilizing controllers for uncertain nonlinear systems has been investigated. Uncertainties including uncertain parameters and structured uncertainties, caused by the mismatch between the mathematical model and the true process, are considered. Two strategies are proposed; a nonhigh gain feedback design is employed to achieve robust stability of the controlled system with matched uncertainties, and a parameter diffeomorphism is used as a high gain control to robustify the cancellation of unmatched uncertainties. The proposed methodologies are implemented on the structure of internal model control (IMC) for the output regulation of a CSTR.