Multiple alignments of nucleic acid and protein sequences are basic investigations widely used for a large number of studies, such as phylogeny, profile construction, structure prediction, and sequence/structure activity relationships. In the last years, many programs and services have been developed to align multiple sequences and to edit and analyze the obtained multiple alignments (1). The most commonly used methods for creating multiple sequence alignments are based on the progressive- alignment strategy, which first estimates a phylogenetic tree and then constructs an alignment of the sequences (named “profile”) following the order in the tree. The best known of these methods is ClustalW (2). There are variants of this approach, such as T-Coffee, which builds a library of both local and global alignments of every pair of sequences and uses a library-based score for aligning two profiles (3), and MUSCLE, which applies horizontal refinement to the built alignment (4). Specific tools to help in the viewing and editing of the alignments have also been developed, including ALSCRIPT and CHROMA that visualize multiple sequence alignments (5,6), as well as SEAVIEW, Jalview, and CINEMA that allow editing of multiple sequence alignments (7–9).