Metallic nanoparticles play a key role in the development of new technologies in recent years. Metallic nanostructures are now being manufactured using a wide range of elements including copper, zinc, titanium, magnesium, gold and silver. These are increasingly used in commercial and biomedical applications and this has led to an increase in the likelihood of nanoparticles interactions with both terrestrial and aquatic ecosystems, as well as the possibility of exposure and damages that happen to animal’s health. This review article focuses on toxicity of silver, copper and gold nanoparticles that affect the spleen in rat model. The nanoparticles produce reactive oxygen species (ROS) that results in oxidative stress, altering cell membrane integrity, vacuolation of cells with ill-defined white pulp, altered architecture and congestion of red pulp and multinucleation of spleen cells. Silver nanoparticles cause more severe effects on rat’s spleen as compared to copper and gold nanoparticles. Further research is required to study the impact of other nanoparticles (lipid nanoparticles, polymeric nanoparticles etc.) on the spleen of rat model.