Structural and floristic study was carried out in Chato Natural Forest, Horo Guduru WollegarnZone, West Ethiopia, with the objectives of determining the floristic composition and structure ofrnthe vegetation found in the area. Data were collected from 40 quadrats, each with 20 m X 20 mrn(400 m2), for trees and shrubs. In addition, 2 m X 2 m subplots were laid within the main plot tornsample herbaceous plants. Vegetation sampling sites were selected by preferential methods fromrnGoogle Earth and coordinates were fed into Garmin eTrex GPS. Altitudes and geographic coordinatesrnwere recorded for each quadrat, and cover/abundance value was estimated for allrnspecies. Height and diameter at breast height of all woody species taller than 2 m and 2 cm werernmeasured.rnOne hundred fifty-four species of vascular plants were identified which were grouped in to 138rngenera and 67 families. Asteraceae followed by Euphorbiaceae and Fabaceae were found to bernthe most abundant families in the study area. Out of these, 23 species were new records forrnWollega floristic region. Furthermore, Chato Natural Forest harbours 12 endemic species; onernof these species was identified as a vulnerable species following the IUCN Red list criteria.rnThree plant community types were identified and named by one/ two or three species with higherrnindicator values. Structural analysis of the Chato Natural Forest revealed a density of 980rnstems/ ha and a total basal area of 65 m2/ ha. The most dominant tree species relatively with thernhighest importance values recorded in the area were Pouteria adolfi-friederici, Podocarpusrnfalcatus, Celtis africana, Mimusops kummel, Pyschotria orophila, Olea capensis subsp.rnmacrocarpa.rnAnalysis of population structure for majority of species revealed normal distribution patterns.rnFloristic comparisons with other similar forests in Ethiopia showed that Chato Natural Forest isrnmore similarity to the moist montane forests.rnKey Words/ Phrases: Chato Natural Forest, floristic composition, FIV, moist montane forest,rnplant community, SIV, vegetation structure.