I am currently in medical school. It is extremely important to get good grades in college, as it will make applying and getting accepted into medical school easier for you. However, grades are not the only thing medical schools look at. They first will look at your MCAT score, second your grades, third you volunteer activities and community service, your personal statement and then your letters of recommendation. So you can make yourself a good candidate in other areas as well if you have a few B's.