Evil Genius FAQ

Infirmary
  If your minions get injured but don't die, they'll come here to get patched 
  back up.

  This room is unlocked when a minion gets injured.  You should also place a 
  time clock in this room, and set it to at least the 1st green square, since 
  most of the healing requires a booth to be manned.  Initially, the infirmary
  can be small.  A 3x3 room should do.  Later on, you'll get bigger stuff 
  that will require a room more like 4x6 or so.  In terms of healing speed and
  effectiveness, from lowest to highest/fastest:

  This room has hardly any heat, and none at all till you build the auto 
  surgeon or x-ray machine, thus it's great to stick at the entrance of your 
  base.

  Pharmacy Booth -> Exam Chair/Auto-Surgeon -> X-Ray Machine

  The Auto-surgeon's bonus is that it doesn't need to be manned.