The estruture of equatorial rainforest near Manaus wasanalysed with regard to abundance., frequency, dominance, naturαl regeneration, sociological - position parameters and a modified "Amplified Importance Value Index (IVIA)", the "Economically-Amplified Importance Value Index. (IVIEA)". 8 plots 20 m x 500 m measuring all plants larger than 5cm and less than 20 cm DBH and 5 subplots of 2 m χ 10 m within each οf theprevious subplots for plants taller than10cm, but less than 5cm DBH were sampled. The minimun numbers of sample plots for each size category ore 2, 6 and 22 respectively for floristic sampling and 6, 18 and 80 respectively for quantitative sampling. The florest is floristically heterogeneous, with 324 species in 173 genera and 57 families recorded from plots. In natural regeneration, individuals of the families Burseraceae, Annonaceae, Rubiaceae and Violaceae predominate, but in mature stand (DBH≥20cm) Lecythidaceae, Sapotaceae, Euphorbiaceae and Caesalpiniaceae predominate. Only a few tree species such as matamatá-ama-relo (Eschweilera odora), ripeiro-vermelho (Corythophora alta), breu-vermelho (Protiumapiculatum) and abiurana-abiu (Radlkoferella sp.) were found in climax communities. Matamatá-amarelo (Ε. odora) is the most important species in the foreststructure, in terms of IVIEA.