There is an increasing public concern about possible side effects of manufactured nanoparticles because of increasing potential for their exposure. Silver nanoparticles (AgNPs) are one of the most commonly used nanomaterials. So, this research aimed to highlight on the effects of AgNPs (20 nm) on kidney and lung. Fifteen adult mice were divided into two groups: control group (5 mice), and silver group (10 mice) which were exposed to 25μl AgNPs (for each mouse) for four hours dermally. After 14 days, the kidneys and lungs of all mice of the two groups were investigated histopathologically and immunohistochemically. The evaluation of immunohistochemical findings was done by the measurement of immunoreactivity score (IRS) of inducible nitric oxide synthase (iNOS). Fourteen days post dermal exposure to AgNPs revealed histopathological changes of the kidney and lung in the form of congestion and inflammatoy cellular infiltration. Renal and lung IRS of iNOS had significant high score in silver group than control group. Our research concluded that dermal exposure to low dose of small-sized silver nanoparticles was not safe because it clearly caused histopathologic abnormalities of the kidney and lung tissues, and so we need further researches for protection suggestion against this toxicity.