Chemopreventive agents can act to prevent or stop genetic mutation that can lead to cancer. Several promising chemopreventive agents include vitamins, minerals and phytochemicals, all of which are obtained from plants. Natural products derived from plants continue to be a fertile source of cure for cancer. In this study, selected Philippine plants were tested for their ability to inhibit chromosomal damage induced by tetracycline in the in vivo micronucleus test (MT). The methanolic extract of Canarium ovatum Engl., locally recognized as pili, showed the most promising activity by reducing the number of micronucleated polychromatic erythrocytes by 54.41% in the preliminary MT screening. Bioactivity-guided fractionation of the crude methanol extract of C. ovatum leaves have identified the most active portion in the hexane fraction. Further isolation and purification will be done to determine the constituent/s responsible for the observed antimutagenic activity in C. ovatum. Identification and characterization of the bioactive compound/s in this plant could be a starting point in the search for other chemopreventive substances, and for the possible synthesis and development of more efficacious agents.