Chemotherapy is usually done to cause many side effects due to the selectivity of therapy targets for breast cancer cells. Therefore, it needs to be a therapeutic solution in the form of a natural chemopreventive agent with minimal side effects on proper use. Bandotan herb (Ageratum conyzoides L.) is thought to have the potential as a chemopreventive agent. Chloroform Fraction of Bandotan Herbs (FKB) have flavonoid compounds as a good potential in HeLa cell apoptosis (cervical cancer) and also nobiletin (one of flavonoid groups) have a good binding to Bcl-xl proteins. This research obtained to know about potentiality FKB as breast cancer chemopreventive agent to binding and inhibits VEGF protein targets. Research methods use in silico and in vivo analysis. As a preliminary test carried out using molecular docking nobiletin compounds against breast cancer cell proteins (COX-2, HER-2, and VEGF). Active compound was carried out using maceration and fractionation methods. Identification of active compounds was carried out using Thin Layer Chromatography (TLC) method. In vivo test, twenty Sprague Dawley rats (40 days, 40-60 grams) classified K.DMBA, K.FKB, K.CMCNa, DMBA+FKB750, and also DMBA+FKB1500. Carcinogenic agents DMBA induce dose given of 20 mg/kg BW twice a week for 5 weeks. FKB was given every day for 2 weeks. After necroption of mammary glands, staining was carried out with Haematoxyllin-Eosin and Immunohistochemistry with VEGF antibodies. Analysis method based on Rf value from TLC, docking score from molecular docking, histology and expression of VEGF at mammary gland histopatology. The results showed that FKB contained flavonoid compounds. In silico test, the best interaction is between nobiletin and VEGF that obtained with a docking score -7.6 kcal / mol. While based on the in vivo test, FKB have potentiality to decrease of mammary gland histological damages. FKB dose 1500 mg/kg BW immunoreactive with VEGF antibodi by the percentage of positive cells at 15,51%.