A mouse found its way into my secret hiding place where it chewed through a soft plastic pencil case containing, among other things, 5 x $100 US banknotes.

The notes are only slightly damaged - the serial numbers are still complete - but here in Chonburi city I haven't been able to find a money changer who will accept them.

Does anyone know whether it is possible to replace damaged US banknotes here in Thailand and how to go about it?

Tried the banks?? Good luck, there, too....

Absent that, I'd look for someone heading back to the U.S. and ask them to do the exchange, and then send me a check for deposit, or deposit to my U.S. bank account.

Mac

Next time you're at the airport easy enough to find a kind yank will give you baht for them at a favorable rate.

Done it myself a few times with different currencies.