In recent years, some graphical representations for genomic sequences have been studied. They provide an opportunity to inspect genomic sequences intuitively and have become powerful tools for analyzing genomic sequences. In this Letter, we have proposed novel graphical representations for protein secondary structure sequences. By our representations, some important information originally hidden in protein secondary structure sequences can be revealed. To illustrate their availability, we apply them to distinguish protein structural classes. The result indicates that they can be used to complement the classification of protein secondary structures. (c) 2006 Elsevier B.V. All rights reserved.