I had to withdraw from 2 classes when my Grandfather was dying because I didn't have time to devote to them and really could have cared less. I had good grades but just missed a bunch of class and knew that I was not doing as well as I could. I ended up WP (withdrew passing) and the med schools did not make a big deal out of it. I also know people that had to withdraw because of a change in their work schedule (so that the class conflicted) and it didn't hurt them. Just have a decent excuse. Now I think a WF (withdrew failing) would have been a bigger deal. Of course, I did retake both classes and got A's in them so they knew it was not that I couldn't do the work.