As the study of central control of multiple organ function becomes more prominent, there is an increasing need for the collection of fixed brain and unfixed organs and tissues from the same experimental animal. Here, we present a protocol for performing carotid artery cannulation, organ and tissue collection, in situ brain perfusion and fixation, and brain dissection in mice. We describe steps for cannulating the carotid artery, harvesting the heart and other organs, and perfusing, fixing, and dissecting the brain.