The primary focus of this project has been the ethnobotany of medicinal plants used on the north coast of Peru. Northern Peru represents the upper sector of the “health axis” of the ancient Central Andean cultural area stretching from southern Ecuador to northern Bolivia (Camino 1992). The traditional use of medicinal plants in this region, which encompasses in particular the Departments of Piura, Lambayeque, La Libertad, Cajamarca, Amazonas, and San Martin possibly dates as far back as the first millennium B.C. (north coastal Cupisnique Culture) or at least to the Moche period (A.D. 100-800). Fieldwork for the present study started in the markets of Trujillo (Mayorista and Hermelindas) and Chiclayo (Modelo and Moshoqueque) in 2001. In this book we provide the North Peruvian data and illustrations from the ethnobotanical database (Skoczen and Bussmann 2005) of 510 medicinal plants organized under the headings: scientific name, vernacular name, plant parts used, administration, preparation, and use. (Bussmann and Sharon 2006b, 2007b).