The present paper deals with the pine wood nematode (Bursaphelenchus xylophilus), which has been placed on the A1 quarantine list in both Europe and Slovenia. The species is extremely offensive, causing fast-paced deterioration in conifers, particularly in those of the Pinus genus and more rarely in those of the Picea, Abies, and Larix genera. The areal, ecological demands, hosts, ecology, and the symptoms of attack on pines of the pine wood nematode are shown. The confirmed vectors (Insecta: Cerambycidae - genus Monochamus) and potential vectors (Insecta: Curculionidae - genus Pissodes andScolytidae) of the pine wood nematode are presented within the framework ofits ecology. The range of potential host plants of the pine wood nematode inSlovenia, climatic conditions, and critical points for the entry and spread of pests are also given. The level of phytosanitary risk presented by the appearance of the pine wood nematode in Slovenia is also evaluated.