You're not a doctor yet, but you'll be expected to behave like one. Patients have little familiarity with the whole medical heirarchy of attendings, residents, interns, and students. To most of them, all the white-coated, stethescoped people walking around are doctors.
Also, you'll notice that after your 2nd or 3rd semester, people in your FAMILY will begin treating you like a doctor. Likely, you'll start getting telephone calls from relatives asking for advice or clarification of medical concepts.
The white coat ceremony is important because it marks your initiation into a very special order. There a few professions that train as hard and as long as physicians do and carry as much social responsibillity (I'm sure you're aware of that). Even after you pass the boards, graduate, finish residency, pass specialty boards, become a fellow of your specialty college, etc...you'll always be a "student" of medicine.
I had the same thoughts about the situation you do when I participated in my white coat ceremony. I didn't ask my parents to attend because I didn't think that the beginning of this whole process was as important or meaningful as the end. I wanted my parents to be there when I graduated. The summer of my second year in medical school my mom died of metastatic lung cancer. It blows me away some times to think that she never lived to see me finish medical school. You've worked very hard to get to where you are. You deserve the opportunity to formally accept the responsibility of becoming a physician-in-training and your parents deserve the opportunity to feel proud of you.
Invite your parents.
[This message has been edited by drusso (edited 07-22-2000).]