Someone once said, "Short sleeved dress shirts are only appropriate if you work at NASA." As for me, I accept that while interns and residents get to parade around the hospital in pajamas (AKA scrubs), and my attending can show up in a polo shirt or even a t-shirt, as a third-year med student I am stuck with trying to look the part and impress anyone who doesn't really know that I don't know anything! Really, though, long sleeves are the traditional approach- you may be able to get away with short sleeves or even no tie once in a while, but eventually some anal retentive, appearance conscious attenting or resident will take note of it and probably let you evaluation reflect their dissatisfaction. I don't like it, but I suck it up and look forward to the pajama days!