Explaining the concept of lung compliance remains a challenge to the physiology teacher because it cannot be demonstrated easily in human subjects and all attempts until now have used only simulation models. A simple device is described in the present article to measure the compliance of the "lung-thorax" combine in human subjects with the caveat that what is recorded is not "lung" compliance and the data generated are of little clinical use. The device comprises a spirometer, a manometer, a mouthpiece, and interconnecting tubes guarded with stopcocks