Many mushroom species have been used by people for different purposes, from past to present. Cultivated mushrooms may show different biological effects depending on the content of the substrate they grown on. The present study aimed to determine the total antioxidant status (TAS), total oxidant status (TOS) and oxidative stress index (OSI) of Pleurotus citrinopileatus Singer mushroom cultivated on five different substrates. The cultivated mushrooms were extracted with ethanol in a Soxhlet device. TAS, TOS and OSI of extracts were determined with Rel Assay kits. The highest TAS (3.125 +/- 0.038 mmol/L), TOS (10.786 +/- 0.313 mu mol/L) and OSI (0.345 +/- 0.014) values were determined in the mushrooms grown on 90% beech sawdust+10% bran. The lowest TAS (2.316 +/- 0.042), TOS (1.246 +/- 0.044) and OSI (0.054 +/- 0.001) values were obtained from the mushrooms grown on 100% poplar sawdust.