This paper gives the results of the first census of trees in the 32.15 ha plot in order to provide tree species richness in Kibira rainforest (Burundi). All trees ≥ 10 cm dbh were permanently tagged and their girth measured. The forest structure pattern analysed were diameter at breast height (dbh), basal area, relative dominance, and relative density, Importance Value Index (IVI) and Family Importance Value (FIV). In total, 6504 trees representing 70 species, 67 genera and 37 families were recorded. Tree density was 202 stems/ha, with a basal area of 21.05m²/ha. Seventeen families were represented by a single species each, eleven families were represented by two species each, five families were represented by three species each, and four families were represented by four species each. The most important families in relation to FIV were Euphorbiaceae, Myrtaceae and Araliaceae. Macaranga kilimandscharica, Syzygium guineense and Polyscias fulva were the most important species in relation to IVI. Two tree species were found to be endemic to the Albertine Rift and one species probably endemic to the Albertine Rift. The Shannon-Weiner index (H') and eveness index (J') were respectively 3.18 and 0.75. This study provides a baseline for the management of Kibira National Park. As local communities still depend on forest resources, conservation awareness-raising and education actions have to focus in nearby villages, and growing some fast-growing native trees in the vicinity of the settlement, would be helpful for local communities, this would reduce their dependence on forest resources.