You can find your serial number in several places:

In Mac OS X

On most computers with Mac OS X, you can find the serial number in the About This Mac window.

Note: A limited number of MacBook Pro computers shipped with a different serial number on the computer label than the one that appears in the About This Mac window. If the About This Mac window says that the computer's serial number is something like 23456VJ0LL, follow the instructions in the next section to check the serial number in the battery bay