Resumo. The floristic forest inventory of Santa Catarina State in Southern Brazil aims at quantifying the forest resources and increasing the knowledge on vascular plant diversity. The study includes sampling of trees, shrubs, herbs and vascular epiphytes. Santa Catarina State¿s surface is about 95,443 km², covered by four major vegetation types: Dense Tropical Humid Forests, Mixed Rainy Forests with Araucaria angustifolia, highland grasslands and Seasonal Deciduous Forests. Forest land cover is about 30%, although extremely fragmentized, especially in the western region. This pilot study has been conducted in Mixed Rainy Forest domain during 2005, measuring 74 sample plots (2000 m² each) randomly distributed in this forest type's area (41,380 km²). Besides the usual analysis of vertical and horizontal vegetation structure, species density data were utilized to construct species/samples matrix that was the basis for Detrended Correspondence Analysis (DCA). The survey results indicate that Myrtaceae, Fabaceae, Lauraceae are the most numerous families, followed by Asteraceae and Solanaceae. The survey registered 133 species with DBH ¿ 10cm, 101 species with DBH <10cm ¿1cm and 105 species with DBH smaller than 1 cm. There is a restricted number of very frequent tree species and a large number (120) of species occurring in less than 10 of the total of 74 sample plots; 46 species are present in only one plot, showing vulnerability of species diversity. According to results of Correspondence Analysis, there are two well distinguished clusters of plots, one of them dominated by typical mixed forest species; the other cluster clearly dominated by supposed to be typical seasonal deciduous forest representants, although located in geographical region until now attributed to mixed forests. The two groups are very dissimilar with respect to their structure and floristics. These results indicate the necessity of new surveys in order to verify the existence of a floristic differentiation along this preliminary established border line. The next steps of Floristic-Forest Inventory could give way to support this hypothesis.