There are a number of studies going on the ill effects of nanosized particles. One such area is particle toxicology which studies the exposure to airborne nanosized particles which occur naturally or through human activities. Studies on ultrafine particles have led to the establishment of nanotoxicology for the purpose of studying the biokinetics of engineered nanomaterials and the adverse effect which they can cause. Most of the studies indicate that ultrafine particles are more toxic when compared to large sized particles. Though developments have been gained in the field of toxicology still researchers are finding it difficult to find out how nanomaterials would be affecting the living organisms. In the case of nanotoxicology interdisciplinary team approach is required in order to arrive at appropriate risk assessment. The field of nanotoxicology is still growing and it is expected to move away from the boundaries of the traditional branch of toxicology of an auxiliary science to one where the knowledge of this field could be put for constructive use in therapeutics.