Nanoparticles have emerged as a transformative tool in cancer care due to their novel approach for drug delivery and diagnostics. Materials having at least one dimension in the range of 1–100 nm are termed as nanomaterials (NMs). The increased surface area and a more targeted drug delivery system make nanoparticles (NPs) ideal for biological applications, but at the same time there is also a potential for them to induce toxicity within the cells. More research is required in the field of biocompatibility before they can be safely used for clinical applications. Understanding biocompatibility and toxicity of NMs is important for advancing from experimental stage to safe and effective cancer treatments.