Most competitive graduate institutions with business administration degrees accept very few students with grade-point averages under a 3.0. This is about a "B" average for most schools. It is at the lower end of the acceptance spectrum. The closer you can get your GPA to 4.0, the more likely it is that you will be considered for the most notable institutions, including those in the Ivy League. A 3.5 GPA or higher is expected for many respected institutions.
Sometimes more important than your GPA is your overall course history. For example, if you scored high marks in the beginning of your education, but your grades trended downward your junior and senior year, this could be a red flag to admissions reviewers. Conversely, if you started out poorly and later excelled, this is a positive demonstration of your potential as a student.
If you are concerned that your grade-point average will not qualify you for your chosen MBA program, there are some ways to boost your current score. Post-baccalaureate classes are for non-degree-seeking students who have already completed their undergraduate studies. Many institutions will allow you to enroll in courses that will benefit your cumulative grade-point average, though you will not receive graduate credit. Many schools limit the amount of post-baccalaureate classes you can take.
While grade-point average is assessing a student's likelihood of succeeding in an MBA program, it is not the only indicator. There are several other factors that admissions boards review when selecting students for their programs. For example, a lower GPA can be balanced out with a high GMAT (the Graduate Management Admission Test) or GRE (Graduate Record Examination) score. An excellent personal statement and impressive letters of recommendation could also help you get in the door of your desired institution.