Although plug-ins such as Chime have helped to facilitate molecule display, its still a pain to the user who does not have it installed getting "broken" plugin icons etc. To help solve this problem, Dave Riddick and I have written some javascript which tests to see what the user has on their system. http://www.ch.ic.ac.uk/motm/pdb_test.html It turns it this is quite a challenge, given that Netscape 2 and 3 differ in what can be tested for, and Internet Explorer is similarly variable. Coping with all permutations is quite complex. Anyway, I enclose the HTML document as it currently stands. If you want to try it for yourself, substitute the refs to pdb files and .gif files in this script for ones of your own. This version tests only for .pdb support, but could easily be extended to cope with other MIME types. The document shows how to produce a table of such types as supported by your own browser. Bug reports etc of course gratefully received. Henry Rzepa. +44 171 594 5774 (Office) +44 594 5804 (Fax)