A study was carried out in a 20 year-old secondary forest situated on the campus of the University of Ucayali, 4 km from the city of Pucallpa, Peruvian Amazon. Botanical and ethno-botanical inventories were made of all trees greater than 10 cm dbh growing on an half hectare plot on very demineralised and acid soil. One hundred and ninety two trees were counted belonging to 22 families and 33 species. The dominant families were (in order of abundance): Euphorbiaceae, Melastornataceae, Leguminosae, Apocynaceae, Combretaceae and Guttiferae. At the species level the following pioneer, fast growing species were most abundant: Croton matourensis, Inga thibaudiana, Miconja eriocalyx, Vismia amazonica and Buchenavia oxycarpa. The total basal area measured was 70 448 cm2. The ethno-botanical survey was made with two informants of the shipibo conibo ethnic group who named 70% of the tree species. One individual knew one or several uses for 66% of the species and the other 73 % of the species.