Dengue hemorrhagic fever is a disease caused by a virus and transmitted by the Aedes aegypti mosquito. Kelurahan Bojongsari is one of the areas with the highest incidence of dengue in Puskesmas Kembaran II East Purwokerto. This study aims to determines the level of vulnerability to dengue endemic areas by using an index ovitrap. This research includes observational with cross sectional design. Data eggs of Aedes sp obtained by ovitrap, counting the number of eggs and ovitrap index . Ovitrap placed inside and outside the house, at 100 selected houses, each 6 ovitrap. Observations conducted once a week for 12 times. The results showed 600 mounted ovitrap average ovitrap index for (IO=9,6%) with IO outside the home is greater (13,5%) than in the home (5,8%). Bojongsari low potential vulnerability to dengue fever (5% ≤IO <20%) and  abundance of Aedes sp obtained  the highest 11 weeks of observation (90 grains / ovitrap) and the lowest was 12 weeks (1 point / ovitrap). Ovitrap use can be an alternative for measuring the level of vulnerability of an area in addition to surveillance as dengue vector control efforts.