Aim: The aim of this study was to determine the proliferation of MCF-7 following irradiation or hyperthermia as alone or pre-treatment with suberosin. Background: Radiotherapy is a major therapeutic modality for the control of breast cancer. However, hyperthermia can be prescribed for relief of pain or enhancing cancer cell death. Some studies have attempted its use as an adjuvant to improve therapeutic efficiency. Suberosin is a cumarin- derived natural agent that has shown anti-inflammatory properties. Objective: In this in vitro study, possible sensitization effect of suberosin in combination with radiation or hyperthermia was evaluated. Methods: MCF-7 breast cancer cells were irradiated or received hyperthermia with or without treatment with suberosin. The incidence of apoptosis as well as viability of MCF-7 cells were observed. Furthermore, the expressions of pro-apoptotic genes such as Bax, Bcl-2, and some caspases were evaluated using real-time PCR. Results: Both radiotherapy or hyperthermia reduced the proliferation of MCF-7 cells. Suberosin amplified the effects of radiotherapy or hyperthermia for induction of pro-apoptotic genes and reducing cell viability. Conclusion: Suberosin has a potent anti-cancer effect when combined with radiotherapy or hyperthermia. It could be a potential candidate for killing breast cancer cells as well as increasing the therapeutic efficiency of radiotherapy or hyperthermia.