The medicinal uses of local flora from the Callejón de Huaylas, Department of Ancash, northeastern Perú, are reported. This geographical area has an old tradition of herbal healing. A total of 33 species have been documented through interactions with village elders, traditional doctors and herbalists. Of the 33 medicinal plant species surveyed in the Callejón de Huaylas, six have not been previously reported, seven have received only minor phytochemical coverage in the literature, and the medicinal uses of seven other plants have not been corroborated with traditional medicinal reports from around the world. The traditional medicinal uses of six medicinal plants have been corroborated with previously published reports but their biological activities have yet to be confirmed in the laboratory. The medicinal uses of four other plants have been corroborated with previously published reports and their biological activities have been confirmed in the laboratory. The purported medicinal use of three plant species could not be confirmed in the laboratory.