Background: The Siberian moth (Dendrolimus sibiricus) is a serious pest of conifers in Russia, Northern Kazakhstan,Mongolia and China. The western border of the pest's distribution in Russia is disputed, but it is present west of the 60th meridian east. The pest has the potential to defoliate a wide range of conifers.Results: The pest is not present in Norway or other European countries, except Russia. Natural spread and human mediated transport are potential pathways for the pest. Human mediated pathways considered are: Living trees for planting, coniferous wood in the rough and foliage and branches. There has been no import of living trees from Russia to Norway during the past 30 years, and there is currently no import of coniferous wood commodities containing bark from areas, where D. sibiricus occurs.Conclusions: The probability of D. sibiricus entry by natural spread is unlikely, mainly because of the geographical distance and the partial sea barriers between Norway and the infested areas. The probability of entry by human mediated pathways is unlikely due to the very limited volume of the import. Should the pest enter Norway, the probability of establishment and spread is unlikely, due to the suboptimal climatic conditions, and the fact that the two dominant conifers in the country, Norway spruce (Picea abies) and Scots pine (Pinus sylvestris), are intermediate and poor hosts, respectively. The potential damage, should D. sibiricus enter Norway, is considered low.