How often should a healthy middle aged adult have a physical examination?

Probably every 1-2 y. There is little or no research that guides us on how often to do check ups. I agree with dr. Klauber that every year or so makes sense, mostly because we learn new information all the time about what cancer screenings, blood tests, vaccines and lifestyle (diet and exercise, mostly) make sense, and it is good to keep current on these. A good resource is an iphone app called my health checklist.
Yearly. Ideally once a year. Your blood pressure should be checked every year as well as your urine. You are with yourself every day so you may not notice abormal things which develop very slowly, eg moles on the skin.