Although heavy metals are naturally occurring elements that are found throughout the Earth's crust, most environmental contamination and human exposure result from anthropogenic activities, such as mining and smelting operations, industrial production and use, and the domestic and agricultural use of metals and metal-containing compounds. The accumulation of heavy metals eventually produces reactive oxygen species that can cause oxidative stress, which may lead to the production of various diseases. The aim of this study was to evaluate the possible effects of iron and zinc on kidney and liver tissues and the positive effects of juglone (5-hydroxy-1,4-naphthoquinone) antioxidant activity, using an immunohistochemical technique. The animals under study were randomly divided into five groups (seven in each group): group I, control; group II, iron (Fe) (600 ppm); group III, zinc (Zn) (400 ppm); group IV, Fe + antioxidant juglone; and group V, Zn + antioxidant juglone. Hematoxylin-eosin (H&E) was applied to determine the histological sides of the damage caused by the heavy metals in the liver and kidney tissues and the effects of the administration of juglone on reducing these damages. Furthermore, the immunohistochemical TUNEL method was applied to determine the DNA damages in the cells. The density of the damage in the liver and kidney tissues of the iron group was higher than in the other groups.