Content: The AZTI’s Marine Biotic Index (AMBI) was developed in 2000. Some years later a software was created for the calculation and made available in the page http://ambi.azti.es. Several versions of this freely available software have been created. In this paper we explain the new AMBI 5.0 version, for Windows 7, which has some novelties regarding the import of data for the calculation, the change of species and the process of saving all the information. Moreover, a new species list, with more than 6300 species from the entire world has been included.