In this study, the most effective agent was Difenoconazole (Score) followed by Asparagus densiflours then Oreopanax guatemalensis plants against Biomphalaria alexandrina snails. The high concentrations of the three tested agents caused a remarkable reduction in hatchability percent of B. alexandrina eggs than the low concentrations. The sublethal concentrations (LC 10 and LC 25) of both A. densiflorus and Score have more destructive effect on the survival, growth and reproductive rates of the juvenile snails than the corresponding concentrations of O. guatemalensis plant. Different sublethal concentrations (LC o and LC 5) of the three agents caused a remarkable elevation in the activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzymes of the snails after the 1 st week of the exposure. The sublethal concentration LC5 of the three tested agents caused pronounced effect on the alkaline phosphatase (ALP) and acid phosphatase (ACP) activities after the 2 nd weeks of the exposure. Total protein, albumin, globulin and albumin/ globulin (A/G) ratio in hemolymph of snails exposed to sublethal concentration LCo of the three tested agents, are differently affected after the 1 st and 2 nd week of the exposure. The histological examinations demonstrated a severe damage in both secretory cells and digestive cells especially in case of Asparagus densiflours and Score.