Written in Iceland around the year 1500, the little book now known only as AM 434a is a treasure trove of medieval medical knowledge. The book lists healing uses for over ninety different herbs. It gives advice on health matters ranging from bloodletting to steam baths to the influence of the moon on health and human life. And it contains a number of magical spells, charms, prayers, runes, and symbols to bring health, wealth, and good fortune. The roots of the healing traditions in AM 434a go back thousands of years before the book itself was written. We are honored to present the first complete English translation of AM 434a. Complete notes and commentary explain this texts's historical and cultural background. Medievalists, historians of science and magic, herbalists, and anyone interested in medieval Scandinavian lore and life will find this book indispensable.