In the history of philosophy, theology, and medicine, Maimonides shares the limelight with Arabic scholars such as Ibn Rushd, Ibn Sinna and Ibn Zuhr, chronologically between the great intellectuals of classical Greece and Rome and those of the later Middle Ages and early Renaissance. Maimonides was a very great philosopher and theologian, usually underrated by the historians. He was also an outstanding medical practitioner and teacher. Moses Maimonides had an incredible literary ability and an encyclopedic knowledge. He wrote extensively in the fields of theology, mathematics, law, philosophy, astronomy, ethics, and, of course, medicine. His medical writings are varied, comprising extracts from Greek medicine, a series of monographs on health in general and several diseases in particular, and a pharmacopoiea. The present essay extracts, primarily from Maimonides' medical writings, his pronouncements dealing with headache. Since most of Maimonides' pronouncements about headache in his Medical Aphorisms were derived from Graeco-Roman medical writers such as Hippocrates, and especially Galen, in regard to these statements Maimonides was merely a compiler--not an innovator. Some of his concepts about the causes of headaches being related to a dysequilibrium of the body humors are clearly medieval in origin. Other statements demonstrate this concern with preventive medicine and the maintenance of a healthy regimen of daily living. Medications to treat illness should only be used if non-medicinal means such as diet and exercise are not effective. The heritage of Maimonides' writings is being more and more appreciated.(ABSTRACT TRUNCATED AT 250 WORDS)