If you have AutoCAD for Mac 2014 or older or AutoCAD LT for Mac 2014 or older, do not update to Mac OS X Yosemite (version 10.10) when it becomes available on October 16, 2014 as they will not run reliably until updates for them are available.
To confirm your version of OS X, click the option 'About This Mac' from the Apple icon at the top left of the desktop. If you see a lower version than 10.10, then your AutoCAD for Mac or AutoCAD LT for Mac will run OK.
According to Autodesk's KB Article, AutoCAD for Mac 2015 is compatible with Mac OSX Yosemite (10.10). AutoCAD for Mac versions 2014 and earlier currently are not compatible with Mac OSX Yosemite (10.10). These versions may launch, but will not operate properly and damage to your project data could occur.
We strongly encourage you to carefully check operating system compatibility with your version of AutoCAD for Mac before upgrading your Mac to OSX 10.10 (Yosemite).
Autodesk plans to release service packs for AutoCAD for Mac 2013 and AutoCAD for Mac 2014 within several weeks after the Yosemite release that will allow those versions to run on OSX 10.10 (Yosemite). When a service pack is released for your version, you'll receive notice in the Mac OS Notification Center. Available service packs are also posted on the AutoCAD for Mac support pages here: