Apple MacBook (13-inch, Mid 2009) - Manual (Page 57)

Chapter 4 Problem, Meet Solution 57
Locating Your Product Serial Number
Use one of these methods to find your computer’s serial number:
 Choose Apple () > About This Mac, and then click the version number beneath the
words “Mac OS X” to cycle through the Mac OS X version number, the build version,
and the serial number.
 Click the Finder icon and open /Applications/Utilities/System Profiler. Click Hardware
in the Contents pane.
 Remove the battery and view the serial number for your MacBook in the battery bay.
For information about removing the battery, see page 35.