Introduction: Genus Phoebe have been reported to produce isoquinoline alkaloids as aporphines, noraporphines, and benzylisoquinolines. Many of these isolates exhibit diversified biological activities, including cytotoxic activity. Objective: The objective of this study is to determine cytotoxic activity of compound isolated from Phoebe declinata againts MCF-7 (breast cancer cell line). Methods: Extraction was done by reflux using n-hexane, antioxidant activity measured by DPPH method and reducing power method, cytotoxic activity measured by MTT assay using MCF-7 cell line, struture eucidation was confirmed by NMR. Results: The antioxidant activity measured using DPPH method for 1 and 2 showed IC50 value of 6.42 and 11.80 μg/mL respectively and using reducing power method for 1 and 2 showed IC50 value of 7.02 and 13.74 μg/mL respectively. Compound (1) and (2) exhibited cytotoxic activity against MCF-7 cells with an IC50 value of 82.978 and 93.179 μg/mL. Conclusion: Compound (1) and (2) exhibited antioxidant activity and cytotoxic activity against MCF-7.