The genusPhytophthora, with 326 species in 12 phylogenetic clades currently known, includes many economically important pathogens of woody plants. DifferentPhytophthoraspecies often possess a hemibiotrophic or necrotrophic lifestyle, have either a broad or narrow host range, can cause a variety of disease symptoms (root rot, damping-off, bleeding stem cankers, or blight of foliage), and occur in different growing environments (nurseries, urban and agricultural areas, or forests). Here, we summarize the available knowledge on the occurrence, host range, symptoms of damage, and aggressiveness of differentPhytophthoraspecies associated with woody plants in Nordic countries with a special emphasis on Sweden. We evaluate the potential risks ofPhytophthoraspecies to different woody plants in this geographical area and emphasize the increasing threats associated with continued introduction of invasivePhytophthoraspecies.