A project aiming at the development of a practical bio-indication system for evaluating forest soil quality was recently started up. The project is funded by the Flemish Forestry Administration responsible for the protected Flemish forests and is managed by the Institute for Forestry and Game Management (IBW). In the project the arthropod fauna of fifty forest stands distributed all over the Flemish Region was sampled by traps operative from spring 1997 till spring 1998. All these plots were also investigated in relation to the physical and chemical properties of their soil and litter layers. The variation of the composition of the spider communities of these stands is unclear when we compare it with the most important litter and soil parameters, but future investigations with more (structural) parameters will hopefully give a good explanation. On a subregional scale, in forests on the same soil type (loam), spider community composition seems to be determined by humidity and density of tree coverage. Spider species forwhich abundance correlates with these major environmental factors are candidate bio-indicators to monitor forest soil quality.