XLSX files are actually a zip file containing various xml files. If you disregard Corion's wise suggestion to use a module available on CPAN, you will need to make your script deal with that. You may be able to learn more about how the file structure works by unzipping the file and looking at the various files and directories/folders contained therein (if you are running windows this can be as simple as changing the file extension to .zip and using the included shell extension to extract the files). This format is not nearly as simple and straightforward to parse as the old XLS format, so unless you plan on using one of the modules on CPAN you should expect to spend some time figuring out how the whole XLSX structure works.