All graduate programs, OT or otherwise, require you to maintain a certain GPA, and generally yes, it's nothing less than a B or B-, or around a 3.0. I already have a Masters degree in another subject, and anything below a B was basically considered a failing grade in that program. Graduate school SHOULD be harder than college; you are trying to specialize in something that you will potential turn into a specific career. With a health science field, I see no problem in having fairly strict standards of achievement. Granted, OTs are not medical doctors or surgeons, and they don't save lives, but they do provide life-improving treatment, and I know if I were a patient, I would want a top-notch therapist. Setting standards weeds out those who are not capable. So for the original poster, I highly suggest buckling down, studying hard and getting some additional help. Talk to your professors and see what needs to be done to bring your grades up. Utilize your fellow students in study groups to review material you are shaky on, and don't be afraid to ask questions.