Physical illness may first declare itself as a disturbance in thinking, mood, or behavior. Recognition of physical disorders is enhanced by informed use of the relevant procedures of physical examination. Objections to physical examination are based on the assumptions that it is overly timeconsuming, is psychotherapeutically contraindicated, or requires unusual skill, but observation and minimally intrusive procedures can provide much information that may exclude emergent organic conditions. Different patients, illnesses, and settings require different levels of examination; the author describes the appropriate procedure for psychotic patients, substance abusers, patients taking psychotropic medications, and other patients.