The present study was conducted to determine of elemental composition, antimicrobial and cytotoxic efficacy of leaves of Olea dioica Roxb. (Oleaceae). The powdered leaf material was digested in ultrapure nitric acid in microwave digester and the elements in digested sample were estimated using Inductively Coupled Plasma with Optical Emission Spectroscope (ICP-OES). The leaf powder was extracted using methanol in Soxhlet assembly and the extract was subjected to phytochemical screening. Antimicrobial activity was assessed against six bacteria and two fungi by Agar well diffusion method. Cytotoxic activity was tested against two cell lines viz., HT29 (human colon carcinoma) and MDA-MB- 231 (Human breast cancer) by MTT assay. Of the elements estimated, the content of calcium and manganese were high among macro and microelements respectively. The extract caused dose dependent inhibition of bacteria and fungi tested. Gram positive bacteria were inhibited to high extent than Gram negative bacteria. Among fungi, Candida albicans was more susceptible to the extract. The extract inhibited the growth of HT-29 and MDA-MB-231 cells in a concentration dependent manner with IC50 value of 131.87 and 140.25μg/ml respectively. The leaves of O. dioica can be a good source of elements needed for normal physiology of the body. The leaf showed marked antimicrobial and cytotoxic potential and thus, it could be used to treat infectious diseases and cancer. Isolation and bioactivity of active principles present in the leaf are under study.