On the sample of five forest management units, we analysed horizontal structure of beech stands by prevalent stand types. We used several diversity indices to describe horizontal stand structure (spatial distribution of trees and differentiation of their DBH). We checked if spatial distribution is influenced by site parameters and cutting intensity. Data was used from measurements on permanent sample plots of the Slovenia Forest Service. The results show mainly average DBH differentiation and random tree positions withsome tendency to clustered and regular arrangement. Trees in younger stages are prone to clustered distribution and their DBH differentiation is smaller. Small DBH differentiation in younger stages is caused by higher intensity of cutting and clustered arrangement is more common on steeper slopes. Several diversity indices can be calculated based on data from PSP, which are suitable mostly for sampling method of reference tree and its four nearest neighbours. A pattern of horizontal stand structure gives a more precise insight in stand structure and is also important when assessing stand stability, biodiversity, stand density and management impact.