4T1 and MDA-MB-231 cells were seeded at 3000 and 5000 per well on 96-well plates. Cells were treated with lobaplatin and microwave hyperthermia at different concentrations (0, 5, 10, 20, 40 µg/ml) and temperatures (37 and 43°C) for 24, 48 and 72 h. Cell viability was detected with the MTS assay (A–F). The combination of microwave hyperthermia and lobaplatin suppressed breast cancer cell viability in vitro (n=6, *P<0.05, **P<0.01, ***P<0.001 based on Student’s t test). Data are presented as the mean ± SD. Means and standard deviations in the bar charts are from three independent experiments.