"An obese patient suffering severely from a post-operative ileus once asked me--in layman's terms--to digitally remove a fecal impaction. I know this falls into the less glamorous events in my career, but no one else was willing to do it for her. It was at the end of my shift and I could have easily just left, leaving it to someone--or not, as such things typically go. I put on a glove and did this unglamorous medical procedure, and the heartfelt gratitude in her eyes taught me that I am not better than anyone, and if I'm pledged to help any patient in need, that is not something from which I get to pick or choose. He or she either needs my help or not. Had I not done this for her, I would be explaining why this was the most important event in my life for quite a different reason."

Wow, what a question. Certainly you expected something similar, like what have you learned from medicine, or what has inspired you the most, things like that. But, the SINGLE MOST IMPORTANT even in your whole LIFE! You can't go wrong saying things like your marriage, the birth of your child, or your day of graduation. (See the 'Entry Level' answer, which is a cop-out, but as said, you can't go wrong.) You might want to steer tangentially, however, and surprise the interviewer with a 'Wow' answer to the 'Wow' question. It will make you stand out from the other candidates and their marriages, births, and graduations. Check out, especially, the 'Experienced Level' example.

"The single most important event in my life was not a single incident, but a dawning on me, through marriage and parenthood, that I am fulfilled putting myself second...or third. This ranking also has served me well in my clinical practice."