The Panel on Plant Health performed a pest categorisation of the Siberian moth, Dendrolimus sibiricus Tschetverikov (Lepidoptera: Lasiocampidae). D. sibiricus is a well-defined and distinguishable species, native to Asian Russia and northern regions of Kazakhstan, Mongolia, China and North Korea, and recognised as a severe pest of Pinaceae conifers, mainly larch (Larix spp.), fir (Abies spp.), spruce (Picea spp.), five-needle pines (Pinus spp.). It has also a potential to develop on non-native Pinaceae: Cedrus, Pseudotsuga, Tsuga. It defoliates healthy trees and kills thousands of hectares of forests. It is absent from the EU and is listed as a quarantine pest in Annex IAI of Directive 2000/29/EC. Plants for planting, branches of conifers and non-squared wood from its distribution range are considered as pathways for the pest, which can also disperse by flight over tens of kilometres. The females produce sex pheromones. Adults do not feed and can survive for about 2 weeks. One female lays up to 400 eggs, attaching them to needles. One generation usually develops in 2-3 years, with larvae passing winter diapause and some undergoing facultative summer diapause. Exceptionally, 1-year generations may occur if the number of degree-days above 10°C is higher than 2,200. Larvae feed on needles through 5-6 instars and pupate in a cocoon on tree branches. Mature larvae have urticating setae on thoracic segments that protect them from enemies and may cause allergic reactions in humans and animals. The contradictory studies regarding the climatic requirements of D. sibiricus make the issue of its establishment in most of the EU territory uncertain, although its host trees are widely present. All criteria for considering D. sibiricus as a potential quarantine pest are met. The species is presently absent from the EU, and thus, the criteria for consideration as a potential regulated non-quarantine pest are not met.