After carefully reading the owner's manual
( which said to expect 3.5 qts ) and after reading the post on Acurazine about transmission fluid change outs, I proceeded to change my transmission fluid and much to my surprise I drained 4 qts & 20 ounces.
It was very good that they recommended carefully measuring what you drain out.
Fortunately for me I had 5 new quarts ready for my first change. Just an fyi.

 

Thanks, I am getting ready to do my first fluid change on my RDX trans soon. My other Acuras have all been about 3.5 qts.
Was your vehicle on a level surface when you did it?

 

Did you lift your car by any chance? I typically drain slightly over 4Qt. Of course that has something to do with how much you fill.