New Zealand's National Pest Plant Accord (NPPA) is a voluntary and cooperative agreement between industry, regional councils, and central government departments with biosecurity responsibilities (primarily the Ministry of Agriculture and Forestry and the Department of Conservation). Plant species included in the NPPA are declared unwanted organisms under the Biosecurity Act 1993, which prevents their sale, propagation, or distribution across the country. Although MAF Biosecurity New Zealand (the lead agency in New Zealand's biosecurity system) has evaluated the potential human health impacts of 202 species considered for inclusion in the NPPA, two species were examined primarily due to their significance to human health: Heracleum mantegazzianum (giant hogweed, cow parsnip, wild parsnip) and Toxicodendron succedaneum (rhus tree, wax tree, Japanese wax tree). As a result of this process, H. mantegazzianum has been listed in the NPPA. In contrast, T. succedaneum was not included in the NPPA, as the latter was deemed to be an inappropriate mechanism for its control. In this article the NPPA process is outlined, and the adverse impacts on human health of these two species are discussed--including symptoms, treatment, and possible management measures.