The paper presents the results of a study performed in 28 ash stands located in Myśleniece and Dynów Forest Districts in southern Poland. The intensity of <em>Fraxinus excelsior </em>disease process was estimated based on the disease symptoms analysis of 1400 trees. The amount of infectious material of <em>Hymenoscyphus pseudoalbidus </em>(anamorph <em>Chalara fraxinea</em>) was estimated by the leaf litter examination on 166 square (0.5 × 0.5 m) plots. The total number of ash leaf rachises and apothecia were counted. The analysis shows that the estimated number of <em>H. pseudoalbidus </em>apothecia may reach from 370 thousand to over 13 million per hectare at a time.