In its broadest sense, The Palouse or Palouse prairie is an ecoregion consisting primarily of native grasses, shrubs, and forbs that originally covered over 16,000 km² of central Idaho, southeastern Washington, and northeastern Oregon. It is estimated that only 1–6% of this habitat remains with much of it having been converted to agriculture. The Kramer Palouse Natural Area is a relatively undisturbed, 11.7-ha remnant of Palouse prairie situated in Whitman County, Washington. During 2004–05 we conducted a light-trapping and hand-netting survey of a set of families of moths, collectively referred to as macromoths, on the Kramer site. The purpose of this study was to document the biological diversity of moths occurring on the site. This paper reports on just over 5,100 specimens and 150 species in 7 families: Cossidae (usually considered a micromoth — one species), Thyatiridae (one species) Lasiocampidae (one species), Notodontidae (three species), Sphingidae (five species), Erebidae (14 species), and Noctuidae (125 species). We collected no Nolidae or Euteliidae and, although Geometridae are considered macromoths, they are not discussed in this paper. Seasonal and subjective abundance information is presented for all species. Although no species of strict conservation concern were collected, our study indicates that remaining areas of Palouse prairie are able to support a significant species diversity of macromoths, which are otherwise uncommon in surrounding areas, and probably represent an ancestral fauna.