The Anopheles culicifacies mosquito is a vector for malaria found in southern India. Control of the Anopheles culicifacies mosquito as a vector needs to be carried out appropriately and in an environmentally responsive manner. The research aimed to examine the mortality and growth of Anopheles culicifacies mosquito larvae due to administration of Stephania japonica L leaf extract and to determine the effective concentration of S. japonica leaf extract in increasing mortality and reducing the growth of Anopheles culicifacies mosquito larvae. A bioassay for mosquito repellence and biocidal activity was performed. Mortality data was obtained by bio testing, which was then tested using probit analysis to determine the effectiveness of the test material. The results showed that larval mortality increased with increasing extract concentration. The extract's effectiveness against the test larvae was demonstrated by the toxicity level of the extract (LC50-48 hours) being 5.01%. Larval growth also decreased with increasing extract concentration; GI (Growth index) values ranged from 0-1, and RGI (Relative growth index) values ranged from 81% to 100%.