"Dress for success" is the motto and your interview attire is important to medical school admissions officers. Whether you like it or not your clothing says a lot about you as an individual and they will leave a lasting impression.
With this mentioned, the best idea is to dress formally, conservatively, and appropriately. Trendy and flashy have no place in an interview no matter what the setting.
Males should wear either a black or blue suit, this is the appropriate interview attire and grays, stripes or other patterns should not be worrn. The suit should fit comfortably and not exhibit signs that it is too small nor too large i.e. showcasing you don't know how to dress professionally or you only do so on rare occassions.
A neutral tie is a must for the interview, therefore leave the flashy, bright and word laden ties at home.
I know you may be tempted to wear sneakers, but don't, it totally messes up the professional image you are attempting to convey. Therefore, wear a pair of dress shoes either in black or dark brown.
Guys, I am a hat man myself but it is not appropriate interview attire to have anything covering your head unless for religious/ethnic purposes.
Please do not wear any unwarranted accessories i.e. chains, earrings, bracelets. These can all be worn at a later time.
Females should wear formal clothing, such as a dress, pantsuit, or matching coordinates. The mini-skirt or anything with a short hem length cannot be worn on an interview. Modesty goes extremely far so no tops which reveal excessive cleavage, conservative is your goal.
Additionally, do not over do it with the make up, use enough to accent your features and that's about all.
Ladies and gentleman, I know perfume and cologne serves a purpose but having your interviewer suffocate over your scent is a bad idea. One to two spays will suffice and anything more is too much. Fragances are to be scented in close proximity and should not announce your arrival.
In general use your best judgement and remember you will be interviewing with medical school representatives. Be clean, well groomed, and free of body odor. Also chewing gum is absolutely prohibited, just don't do it!
Let your mind, intellect, and personality make the lasting impression not superficial articles of clothing.