Multi-walled carbon nanotubes functionalized with diethylentriaminepentaacetic dianhydride (DTPA-MWNT) and radiolabeled with Indium-111, having therapeutic and diagnostic applications, were tracked in the systemic blood circulation and the excretory system using a microSingle Photon Emission Tomography (microSPECT) scanner. Quantitative Kaiser test was used to determine the number of free amino groups on the DTPA-MWNT. A suspension of PBS and DTPA-MWNT was intravenously injected by tail vein in the Wistar rats and the urine production, water consumption and body weight were observed for 24 hours. The rat was necropised and tissues of various organs were fixed and observed with a Nikon Microphot-FXA microscope coupled with digital camera. The Length of DTPA-MWNT used in the study is larger than the dimensions of the glomerular capillary wall, so it was excreted through urine after 24 hours post-administration.