The aim of this project was the determination of the biokinetics of TiO2 nanoparticles (NP) in the whole body of healthy adult rats after NP administration to the respiratory tract – either via inhalation or instillation. Here we offered applying our previously developed methodology of quantitative biokinetics using radio-labelled NP. Quantitative biokinetics means that not only the NP absolute contents and concentrations of NP in primary and secondary organs and tissues of interest are determined but also those of the remaining body (carcass) and those in faecal and urinary excretion.