[This answer assumes that you are in the US. I have no idea what the laws are outside the US. I'm not a lawyer, I'm not representing you, and this is not leg

[This answer assumes that you are in the US. I have no idea what the laws are outside the US. I'm not a lawyer, I'm not representing you, and this is not legal advice.] Assuming it is for "hundreds" (and not thousands/tens of thousands), if you don't pay this is what is likely to happen (if it were a lot of money, the facility might file suit against you. They aren't gonna for hundreds): First, you might get lots of copies of the bill. (You also might not). Then you'll get a letter about them going to collections. Then you'll probably never hear from them or anyone again (maybe one letter asking you to pay), but your credit report will show an unpaid collection. If you previously had perfect credit, your credit score will fall considerably*. After seven years, it will fall off your report, and after that nobody will ever mention it again. If you seek service at the facility again, it is quite possible that they will require you to pay the bill before agreeing to serve you again, and they might also require payment for the new service upfront. *medical billing is so bad that the various credit-scoring programs have all been tweaking their rules for medical collections over the past few years, and they keep threatening to just stop counting medical collections toward credit scores. One of the major credit scorers, for example, now ignores all medical debt less than a year old and less than $2500 in amount, on the grounds that it is generally impossible for a patient to effectively dispute even obviously-incorrect bills until after they appear on a credit report (at which point the laws governing credit-reporting grant the consumer more effective ability to dispute), and therefore recent/small medical collections are not a useful predictor of whether a consumer will pay their other (more likely to be legitimate) debts.