In the fifth edition of The Autonomic Nervous System, Appenzeller, now with the collaboration of Oribe, has expanded both the scope and the depth of the discussions on basal, adaptative, and abnormal autonomic function. While maintaining a strong emphasis in mechanism of adaptation to environmental challenges, this new edition incorporates deeper discussion on autonomic adaptation to hypoxia and mountain medicine, adaptation to microgravity, and testing of autonomic function. This book has several strengths as well as weaknesses.