Soil was treated with olive mill waste water (OMW) in order to study the effect of this agriculture waste on soil fungal population. Changes in fungal composition were observed after soil pollution. In order to test OMW selective pressure, growth kinetics of Penicillium cyclopium, Scopulariopsis brevicaulis and Cladosporium cladosporioides were studied on solid media supplemented with different OMW concentrations. S. brevicaulis and C. cladosporioides did not grow at OMW concentration higher than 50%, while at concentrations lower than 50% a growth decrease was observed. Instead, P. cyclopium was able to actively grow at all concentrations of OMW tested. Therefore the OMW can influence and modify the soil fungal homeostasis.