Objectives: Static magnetic field (SMF) was previously in practice for the therapy of some diseases and it has been thought that it may be a reliable supportive technique. The aim of this study was to find out the synergistic effect of SMF administration with flavonoids in terms of apoptosis on breast cancer cell lines. Material and methods: The effects of flavonoids on the proliferation of breast cancer cell lines were observed by MTT cell viability test. The cells were treated with SMF + hesperetin and SMF + quercetin. Apoptosis rates and Bax, Bcl-2 protein levels were detected by flow cytometer and Western Blot, respectively. Results: Cell lines were treated with quercetin and quercetin + SMF, substantial amount of cells [3.96, 4.86, 11.40% for MCF-7 and MDA MB-231 cell lines, respectively (p<0.001)] were mainly in the apoptotic phase. The apoptosis rates of hesperetin and hesperetin + SMF were 2.53, 6.06, 10.10% (p<0.001) for MCF-7 and MDA MB- 231 cell lines, respectively. Bax:Bcl-2 ratios were significantly increased after flavonoids + SMF exposure (2.7 vs. 1.6 fold (p<0.0001) in hesperetin + SMF group and 1.8 vs. 1.3-fold (p<0.0001) in quercetin + SMF group for MCF-7 and MDA MB-231 cell lines, respectively. Conclusions: SMF might support the anti-cancer properties of flavonoids, on breast cancer cells via mitochondriarelated apoptosis pathway.