Gentamicin and streptomycin are the most common antibiotics in group of aminoglycosides. However, due to its side effects, there are some limitations in the use of gentamicin and streptomycin. One of the complications of gentamicin and streptomycin is nephrotoxicity. Therefore, the recognition of extent and intensity of this complication can be useful in preventing or decreasing of this in gentamicin and streptomycin therapy.

In this research, the difference of nephrotoxicity resulting from these two drugs became clear histopathologically.

Thirty rats (field mice) weighing approximately 250 grams each were divided into 5 equal groups. These groups were injected in the following procedures.

The first group received normal saline injections and the second and the third group received gentamicin and the fourth and fifth groups received streptomycin all for 80 milligrams per kilogram of weight and for ten days.

At the end of the tenth day, the mice of the first, second and fourth groups were euthanised and renal lesions were registered histopathologically. The third and fifth groups were kept for ten more days while interrupting the drug. Finally, at the end of the 20^th day, they were euthanised and the recovery extent was histopathologically registered.

Ultimately, we reached the conclusion that the extent of nephrotoxicity of gentamicin was more and its recovery was less than streptomycin.

The reason of this phenomenon seems to be due to less density of streptomycin in the kidney cortex and low plasma protein binding of this drug that results in the more glomerulous filtration of streptomycin.