This is the first detailed report on plant-parasitic nematodes occurring in Idaho and eastern Oregon, U.S.A. Plant-parasitic nematodes from 186 soil samples collected in 26 counties were identified. Twenty-five nematode genera were found. Forty-seven species including two evidently undescribed are reported in the region for the first time. The new records are in 11 genera: Criconemella, Geocenamus, Gracilacus, Hemicycliophora, Helicotylenchus, Merlinius, Paratylenchus, Pratylenchus, Trophonema, Trophurus, and Tylenchorhynchus. Other nematode genera found were Anomyclus, Aphelenchoides, Aphelenchus, Coslenchus, Ditylenchus, Heterodera, Hoplolaimus, Megadorus, Meloidogyne, Paratrichodorus, Psilenchus, Trichodorus, Tylenchus, and Xiphinema.
