Nanotechnology is a major scientific and economic growth area across the globe. In recent years, with the advent of nanotechnology, application of TiO2 nanoparticles in sunscreens & cosmetics, paints & coatings, water treatment, antimicrobial agents, health care products such as bandages and manufacturing of energy storage devices is paramount. It confers significant release of these nanoparticles into environment thereby raising concerns about their adverse impact on the ecosystem. Although there are studies reporting the ecotoxicity of TiO2 nanoparticles, reports on toxicity of TiO2 nanoparticles on ecosystem engineers such as earthworms are scarce. In this regard, the book presents vital aspects of TiO2 nanoparticle toxicity in earthworm Eisenia fetida. It depicts the significance of physicochemical properties of titanium dioxide nanoparticles in eliciting oxidative stress in earthworms. It disseminates knowledge about ecotoxicological evaluation of nanoparticles thereby assisting in environmental monitoring of nanowaste in future.