Some two-dimensional (2D) graphical representations of DNA sequences have been given by Gates, Nandy, Leong and Mogenthaler, Randie, and Liao et al., which give visual characterizations of DNA sequences. In this Letter, We introduce a nondegeneracy 2D graphical representation of DNA sequence, which is different from Ranie's novel 2D representation and Liao's 2D representation. We also present the nondegeneracy forms corresponding to the representations of Gates, Nandy, Leong and Mogenthaler. (c) 2005 Elsevier B.V. All rights reserved.