It is known that Silver Nanoparticles and silver nitrate have harmful effects on the surrounding organisms, which may cause several damages to these organisms, whether harmful or beneficial. The aim of this study is to detect damage caused by silver Nanoparticles and silver nitrate to land slugs Lehmannia nyctelia. In this study, slugs have been exposed to different concentrations of silver NPs and silver nitrate for 15 days. Histological examinations were performed in each digestive gland, kidney and gonads. The digestive gland appeared several alterations after exposed to different concentrations (0.04, 0.08, 0.4, 0.8 g/L). A clear change in the shape of the cells was noticed where, cells became more flattened and many cells were damaged. The cavity of each tubule increased in size and filled with some remains of damaged cells and the cells became empty from inside. The histological study of the kidney revealed a deterioration in some cells, widening of the spaces between tubules and an increased in connective tissue size than the normal size. The gonads showed clusters of cells in some places, spermatozoa lost the normal shape of the tail. In conclusion the result indicated that silver Nanoparticles and silver nitrate can cause damage in histological structure of the slug may cause harmful effects on the terrestrial environment.