HELM is a web tool designed to automate the analysis of protein sequences searching for alpha helix motifs. This analysis can be useful in protein engineering studies, aimed at the identification of regions to be modified in order to obtain more suitable features of local and/or global stability. AVAILABILITY: The tool is available to academic and commercial institutions at the URL http://crisceb.area.na.cnr.it/angelo/ PROTEIN_TOOLS/HELM/ CONTACT: angelo@crisceb.area.na.cnr.it