Problem solved! Sorry, but it seems all I needed to do was show the atoms and bonds. Chimera is reading the file it just doesn't show anything until you tell it to show atoms and bonds. Another surprise with the new Chimera version is that it automatically displays my nucleic acid files with slab bases, filled sugars, and a backbone ribbon. Is there anyway to shut this off so I don't have to go in and manually do it each time I open a nucleic acid structure? Thanks, Dave -------------------------------------------------------- David Chenoweth NIH Postdoctoral Fellow Swager Research Group Massachusetts Institute of Technology Chemistry Department, 18-053 77 Massachusetts Avenue Cambridge, MA 02139 Email: dcheno@mit.edu Lab Phone: 617-258-6537 --------------------------------------------------------