The present study was conducted to assess the feasibility of fernThelypteris dentata for revegetation of fly ash (FA) landfills. In this context, the impact of metal accumulation on malondialdehyde (MDA), cysteine and non-protein thiols (NPSH) contents was determined in T. dentata grown in FA amended with garden soil (GS) in different ratio at 30 days and 45 days after treatment. The experimental results revealed that this fern species possesses internal defense mechanism against toxicity of heavy metals of FA. There was a significant increase (P≤0.01) of MDA, cysteine and NPSH observed in the below ground (i.e. roots including rhizome) as well as above ground part (fronds) of T. dentata grown in 100% FA as compared to the plant species grown in 100% GS. The results showed a high tolerance potential of this fern to endure oxidative stress by metabolic adaptations and showing feasibility of using T. dentatain the revegetation/stabilization of FA landfills.