This study was purposed to investigate the inhibitory effect, apoptosis, Bcl-2 and P-gp expression of K562/AO2 cells by hyperthermia combined with adriamycin. The working concentration of adriamycin against K562/AO2 was determined by MTT assay. The hyperthermia and chemotherapy were used alone or in combination, then the cell survival rate was detected at 48 hours. The inhibitory effect was evaluated by MTT assay. The apoptosis rate, Bcl-2 and P-gp expression of K562/AO2 were determined by flow cytometry. The concentration of adriamycin in the experiment was defined as its IC(50) at 48 hours action. The results indicated that the hyperthermia at 40, 41 and 42 degrees C for 60 minutes showed obvious inhibitory effect on K562/AO2 cells (p < 0.01). Adriamycin chemotherapy combined with hyperthermia showed more obvious inhibitory effect on K562/AO2. According to flow cytometric analysis, the hyperthermia and adriamycin used alone or in combination could obviously increase the apoptosis rate and down-regulate Bcl-2 and P-gp expression of K562/AO2 cells (p < 0.01). It is concluded that the adriamycin chemotherapy combined with hyperthermia for 60 minutes shows obvious inhibitory effect on K562/AO2 cells, which increases the apoptosis rate and down-regulates expression of Bcl-2 and P-gp.