Introduction: Goniothalamin (GTN) is a plant styryl-lactone that has been reported to possess anticancer properties. However, limited studies were conducted to explore the selectivity of GTN to human cancer cells in comparison with normal human cells counterpart. The aim of this study was to evaluate the cytotoxicity and selectivity of GTN in human cancer cells lines of osteosarcoma cells (Saos-2), adenocarcinoma alveolar basal epithelial cells (A549), breast carcinoma cells (UACC-732), breast adenocarcinoma cells (MCF-7), colorectal adenocarcinoma cells (HT29). Human bone marrow-derived mesenchymal stem cells (HMSC) served as a control normal cell. Methods: The an- tiproliferative activity of GTN was assessed by MTT assay for 24, 48 and 72 h of incubation time. Then, the half maximal inhibitory concentration (IC50) and the selectivity index (S.I) were calculated to examine the potency and selectivity of GTN. Results: GTN has significantly exhibited concentration and time-dependent inhibitory effect to all tested cancer cells with the lowest IC50 values ranging from 0.62±0.06 to 2.01±0.28 µg/ml after 72 h. Besides, GTN was found to be better than doxorubicin, DOX (positive control) in term of its selectivity towards cancer cells as higher S.I values between 2.86±0.31 to 10.02±1.49 were determined for all the cancer cells. Conclusion: This study concludes that GTN fulfills the basic criteria as an effective therapeutic agent by possessing a very strong range of anticancer activity with less toxicity towards the normal cells. Thus, GTN could be considered as a promising alternative to present chemotherapeutic drug in cancer treatment.