My therapist/pdoc always wore dress slacks, a shirt, and tie. I was really surprised when I interviewed new therapists and pdocs how casually they were dressed. Khakis and polo shirts. I have the strangest idea that my new psychiatrist wears doctors' coats, but though I've seen him 4 or 5 times I really am not sure. He sits across his desk and the client's chair is back from it, so I haven't noticed for sure what he does wear.