The main objective of this study is to characterize the structure of the Vyanda Forest Nature Reserve (RNFV) in southwest Burundi. Data were collected in 34 square plots with a side of 20 m where all individuals of woody species with a circumference of at least 15 cm were inventoried. The structure was analyzed by calculating the density, the basal area and the value index of importance of the species and the establishment of the circumferential structure. The inventory results reported 23 woody species totaling 691 individuals representing a density and basal area of 508.09 stems/ha and 12.33 m²/ha respectively. Uapaca nitida var. suffrutescens is the most abundant species in the RNFV with a relative density of 37.63 and an absolute density of 193.38 stems/ha. This species is also the most dominant with a relative dominance of 64.73 and an absolute basal area of 7.99 m²/ha.It appears that five woody species namely Uapaca nitida var. suffrutescens (IVI = 109.31), Anisophyllea boehmii (IVI = 47.43), Uapaca nitida var. rufopilosa (IVI = 22.20)), Parinari curatellifolia (IVI = 14.71), and Brachystegia utilis (IVI = 12.91) are the most ecologically important. Establishing the circumferential structure revealed an “inverted J” shape indicating the dominance of small individuals. Sustainable management strategies for this protected area should be implemented to mitigate its degradation.