The effect of chitosan and nano-chitosan on the land snails Eobania vermiculata and Monacha obstructa was investigated. Under laboratory conditions, the LC₅₀ values recorded, 8.6%. and 6.9 % for E. vermiculata and M. obstructa treated with chitosan, respectively. On the other hand, snails treated with different concentrations of nano-chitosan, resulted in LC₅₀ values of 1.4% and 0.16% for E. vermiculata and M. obstructa, respectively. The effects of both compounds on certain biochemical parameters were recognized. When chitosan and nano-chitosan were applied at the LC₅₀ level, the total protein activities showed significant increase compared to control for E. vermiculata. The same compounds showed a significant decrease in the level of total protein for M. obstructa . Natural chitosan increased the level of  total lipid from 32.5 to 52.5 g/dL after the treatment. While nano-chitosan  increased it up to 78.33 g/dL for E. vermiculata. Also, natural chitosan increased the total lipid from 25.0 to 37.5 g/dL for M. obstructa compared to an increase of 52.5g/dL attained by the effect of nano-chitosan particles.