The article contains basic information on the biology and distribution of Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle, as well as analysis of the factors for possible acclimatisation of pine wood nematode in the Republic of Karelia. Pest risk analysis is an important tool in modern plant quarantine studies, based on multi-factor study of various environmental indicators and their dynamic variability, enabling the study of the risk of invasions, establishment and spread in a new area for a particular quarantine organism. Timely assessment of pest risk helps select effective phytosanitary (quarantine) measures according to the biology of the pest and its dispersal pathways. We provide a map of Karelia with predominant conifers and summer and winter isotherms. It is concluded from the phytosanitary risk assessment that the pine wood nematode can survive in Karelia due to predominance of Scots pine (Pinus sylvestris), the host plant of this pest, throughout the region and the wide distribution of Monochamus beetles, which can host nematodes of the genus Bursaphelenchus. However, the climatic conditions in Karelia will not favour intensive development of Bursaphelenchus xylophilus due to the absence of prolonged periods with high ambient temperatures.