Background: Regarding to the applications of Gold nanoparticles in the medical and biological fields, the study on its toxic effects on organisms is essential.

Materials and Methods: In this study, the effect of intra-peritoneal injection of Gold nanoparticles (10nm, 100ppm concentration) on changes in the renal parameters (urea, uric acid and creatinine) at different times after treatment (10, 20, 30 and 40 days) in mice were studied.

Results: Results of the study showed that the average amount of urea and uric acid significantly increased after 20 days of treatment compared to the other groups (P<0.01), while 40 days after the injection all the changes went back to normal. The average weight of the mice and the histological structure of the kidney did not show any abnormality as compared to the control group.

Conclusion: It seems that the application of Gold nanoparticles in low concentrations (100 ppm) in biological system has no stable and long-term toxic effect on the animal body and probably the reticuloendothelial system excretes the nanoparticles.