Hi Mike,
There are several possible routes to achieving this, but a concise one is the command:

label  ~  element.H

where the "~" is a logical NOT.  
<http://www.cgl.ucsf.edu/chimera/docs/UsersGuide/midas/atom_spec.html#combinations>

Or, you could label all atoms and then unlabel hydrogens, or do the menu equivalents of either of those routes.

I hope this helps,
Elaine
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Elaine C. Meng, Ph.D. 
UCSF Computer Graphics Lab (Chimera team) and Babbitt Lab
Department of Pharmaceutical Chemistry
University of California, San Francisco

On Oct 21, 2010, at 1:59 PM, Michael Day wrote:

How would I label all atoms in a structure without labeling hydrogen atoms? I'm trying to label a small molecule with about 60 non-hydrogen atoms.