When I shadowed, the otolaryngologist, he gave me a white coat, so i looked just like the other medstudents. I tried to wear nice shoes (not sneakers), and dress pant. Jean are rather casual. If it's a formal program with a hospital, they should have a dress code. They had specific guidelines when I worked in ER. Tie is really neccesary. But, something nicer than jeans would be good.