I upgraded my Mac to a OSX 10.11.4, and sadly I found my theano cannot be imported anymore. Here is information about my machine:
➜ ~ gcc --version
Configured
The problem comes from an interface change in Xcode 7.3. It is fixed in the current master of Theano and there will be release 0.8.1 next Tuesday (2016/03/29) that will be 0.8.0 + the fix.
In the meantime you can either run the master: http://deeplearning.net/software/theano/install.html#bleeding-edge-install-instructions or install version 7.2 of the command line tools and select those with xcode-select to make Theano work.