Response of vector mosquitoes against insecticides was not only occurred after contact but Excite-repellency test for target mosquitoes was recommended by WHO, before the insecticide was used for indoor residual spraying (IRS) or impregnated bed nets. Studies on repellency and efficacy of the insecticide alphacypermethrin had been conducted against An. sundaicus the malaria vector in the coastal areas. Mosquito samples were collected from two villages e.g. Pasir Gedangan and Jatimalang, Purwodadi Subdistrict, Purworejo Regency, in the province of Central Java, in the period from June-August 2000. The results of the study showed that only few mosquitoes were killed (exit from the test box) for all dosages that were evaluated (12.5 mg/m2, 25.0 mg/m2 and 50.0 mg/m2) i.e. 9-17% mortality. The mortality of the mosquitoes was significantly higher (p<0.05) for dosages of 12.5 mg/m2 and 50.0 mg/m2. The number of mosquitoes escaping from the test box in 60 minutes exposure could not reach LT50 and LT90. The result of the study also indicated that this species was susceptible against insecticide alphacypermethrin in 100% mortality.