Abstract Motivation Motif-HMM (mHMM) scanning has been shown to possess unique advantages over standardly used sequence-profile search methods (e.g. HMMER, PSI-BLAST) since it is particularly well-suited to discriminate proteins with variations inside conserved motifs (e.g. family subtypes) or motifs lacking essential residues (false positives, e.g. pseudoenzymes). Results In order to make mHMM widely accessible to a broader scientific community, we developed Leitmotif, an mHMM web application with many parametrization options easily accessible through intuitive interface. Substantial improvement of performance (ROC scores) was obtained by using two novel parameters. To the best of our knowledge, Leitmotif is the only available mHMM application. Availability and implementation Leitmotif is freely available at https://leitmotif.irb.hr. Contact sinisa@heuristika.hr or ivan.vujaklija@fer.hr Supplementary information Supplementary data are available at Bioinformatics online.