One of the important veterinary parasites is Sarcoptes scabiei which causes sarcoptic mange. The traditional treatment causes environmental hazards and might lead to resistance in the target species. The study was aimed to evaluate the ef?cacy of the methanol extracts of Enteromorpha intestinalis and Cladophora crispata algae against sarcoptic mange in vitro and in vivo. Forty-two rabbits infested with S. scabiei mites are used. LT50 and LC50 were calculated using probit analysis. The intensity and recovery of the lesion were described using grade codes and mites examination. All extracts concentrations have killed all mites in vitro at 2 h post-treatment, The LT50 values of E. intestinalis extract at 2, 1, and 0.5 g/mL were 0.5165, 0.7626, and 1.1982 h, respectively, the LT50 values of C. crispata extract at 2, 1, and 0.5 g/mL were 0.4656, 0.5165, and 0.6641 h, respectively. The LC50 values of E. intestinalis extract at 0.5 and 1 h post-treatment were 1.5869 and 0.3436 g/mL, respectively, the LC50 values of C. crispata extract at 0.5 and 1 h post-treatment were 1.9358 and 0.6252 g/mL, respectively. 2% of E. intestinalis and C. crispata is exhibited completely cleared infesting mites in vivo at 16 and 22 days post-treatment, respectively. The clinical sarcoptic mange was completely cured at 22 days post-treatment by the concentration of 20% of C. crispata extract, followed by 20% of E. intestinalis extract. The results indicate that the E. intestinalis and C. crispata extracts could be used for effective control of sarcoptic mange
