Hi Pasquale, If your structure all got put into a single residue named UNK, that typically means that your file was missing the @SUBSTRUCTURE section (http://www.tripos.com/mol2/mol2_format33.html#1370). There is an entry in our bug database (#3518) for better handling of files with missing @SUBSTRUCTURE sections. I will add your name to that report so you'll know when it gets fixed. For now, you will have to edit your file and add an @SUBSTRUCTURE section "by hand". --Eric Eric Pettersen UCSF Computer Graphics Lab pett@cgl.ucsf.edu http://www.cgl.ucsf.edu