The development of the geological and medical sciences shows overlap through numerous historical threads, some of which are investigated here by an international authorship of geologists, historians and medical professionals. Some of the medical men considered here are the relatively well known Steno, Parkinson, William Hunter and Peter Duncan, as well as several more obscure individuals such as Sperling, Hodges, Lemoine, Siqués and a number of Italians. Their work included foundational geological studies, aspects of hydrogeology and the nature of fossils. The therapeutic use of geological materials has been practised since ancient times. A suite of magico-medicinal stones, some purportedly harvested from the bodies of fabulous animals, have ancient folklore roots and were worn as protective amulets and incorporated into medicines. Medicinal earths were credited with wide-ranging medicinal properties. Geology and Medicine: Historical Connections will be of particular interest to Earth scientists, medical personnel, historians of science and the general reader with an interest in science.