The first comprehensive Check-List for the trees of Sarawak was compiled by Dr. J.A.R. Anderson and published in 1980, to meet the need for scientific forestry in the fields of forest inventory, silviculture and ecology. Anderson’s Check-List contains over 2,500 species, and he predicted at the time that more would be added in the years to come. In the past two decades numerous new plant specimens were obtained and added to the Forest Department Herbarium collections. In the early 1990s, the Tree Flora of Sabah and Sarawak (TFSS) Project was initiated. Many nomenclatural changes were made and new species described. Collaborative taxonomic research between the Forest Department Herbarium and the herbaria in Kew and Leiden has also resulted in the revision of many species. A total of 3,453 species from 599 genera and 110 families are contained in this New Check-List. This number excludes many specimens that could not be reliably named. This is a significant increase of nearly 1,000 species from that recorded by Anderson. The New Check-List is based on material housed in the Forest Department Herbarium in Kuching. As far as possible, the scientific names have been updated based on the Tree Flora of Sabah and Sarawak, Botanical Research and Herbarium Management System (BRAHMS) and International Plant Names Index (IPNI). For those families that have not been revised by the TFSS Project, the names given in the herbarium specimens are followed. This New Check-List is largely the effort of the first author who started to compile a list of the local names and their equivalent scientific names as a learning tool in 1985, with some help and input by the second author. It is not intended to replace Anderson’s Check-List but rather to complement it. Anderson’s Check-List contains valuable ecological information on the species, as well as a list of trees of the peat swamp forest, that are not found in the New Check-List. As a sequal to this tree check-list, a second check-list of the non-tree flora is being compiled. It will contain about 3,000 species and will be the first for Sarawak.