Two reasons. The first one is easy, to pay for the rental. The second reason is more complicated especially if we are billing your insurance. There is no way to put this delicately. Some people are not honest. Our equipment is very expensive and we want it back after you are done using it. The credit card is used as a deposit on the equipment to ensure that you will return it and to ensure that your balance will be paid. If you are concerned about using your credit card please call your credit card company and ask them how you are protected. You may also call one of our Patient Care Representatives at 1-877-301-4276.