Populations of small balsam Impatiens parviflora have been studied in the Male Karpaty Mts., SW Slovakia, since 1981. Largest plants were found in ecotones along forest margins (near roads) and in clearings (few years after cutting). A monospecific stand (stand height, density and biomass were 1.24m, 23 i m-2 and 1100 g m-2, respectively) growing along a forest edge on clear-cutted area at Bratislava-Zelezna Studienka was chosen for a detailed analysis of size and biomass structure in the stage.