Yes. A very bad one
Unpaid medical bills (or any other bills) that wind up with collection agencies have an adverse affect on your credit report and score.
Your credit score may drop by up to 120 points because of a single collection account. Once an unpaid bill reaches collection, it is reported to your files and immediately affects your score.
The credit score algorithm doesn’t distinguish between unpaid medical bills to other type of bills. It’s all the same as far as credit score goes.
You really need to take care of this debt. The collection agency can come after you in various ways, including filing a law suit. If they get a judgment, they can even garnish your wages and attack your bank accounts and property.
See why-pay-off-debts.html and how-to-pay-off-debt.html for more information and tips on dealing with collection agencies.