Marine algae have shown to be the most promising sources of new bioactive compounds against different snails transmitting parasites. In the present study three species of marine algae. Ulva lactuca (U. lactuca) , Pterocladia capillacea (P. capillacea) and  Jania rubens (J. rubens)extracts having Lc₅₀ values 121, 111.3 and 127 ppm respectively, have been  evaluated to select the most potent one as molluscicides against Lymnaea natalensis (L. natalensis) snails for controlling fascioliasis. The protein content for L. natalensis snail tissues after treatment with U. lactuca, P. capillacea and J. rubens extracts was 243.6± 0.03. 196.6 ± 0.03 and 280.3 ± 0.05 µg/ml respectively and there was a significant decrease in protein contents of the treated snail tissues than controlled ones. The electrophoretic separation of snail tissues treated with mentioned algal extracts using Sodium Dodocyle Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE), revealed several bands for each algal extract ranged from 21 to 205 kDa. The alteration in electrophoretic profile of treated snails includes appearance of new protein bands, disappearance of bands and change in the concentrations of shared bands with control snails. Based on these alterations, it could be concluded that the algal extracts have molluscicidal effect on L. natalensis snails.