Objective: The aim of this study was to investigate the relationship between p38MAPK activity and apoptosis during the drug resistance of breast carcinoma cell lines. Methods: Using p38MAPK special inhibitor SB203580 to analyze the effect on the cell apoptosis of MCF-7/ADM cell. Cell apoptosis was analysed by PI staining and flow cytometry (FCM) (F test). 50% inhibition concentration (IC50) of adriamycin on MCF-7/ADM was determined by MTT method (F test) in vitro. MDR-1 mRNA expression was detected by RT-PCR (F test) and Western Blot (F test) respectively. Results: After SB203580 24 h action the MCF-7/ADM’s apoptosis rate was 26.73 ± 4.90%, higher than the control group and untreated group (F = 143.80, P < 0.001). The sensitity to the ADM was improved significantly (F = 148927.1, P < 0.001), and the reversal effect of treat SB203580 group was 68.45%. The P38MAPK protein (F= 685.419, P < 0.001) and MDR-1 mRNA expression after SB203580 24 h action were lower than the control group and untreated group (F = 9139.24, P < 0.001). Conclusion: P38MAPK signal way plays an important role in drug resistance of breast carcinoma cell. p38MAPK can protect MCF-7/ADM cells from apoptosis, and blocking the p38MAPK signal way can increase the apoptosis for breast carcinoma drug resistance cell lines. Objective: The aim of this study was to investigate the relationship between p38MAPK activity and apoptosis during the drug resistance of breast carcinoma cell lines. Methods: Using p38MAPK special inhibitor SB203580 to analyze the effect on the cell apoptosis of MCF-7 / ADM cells. Cell apoptosis was analyzed by PI staining and flow cytometry (FCM) (F test). 50% inhibition concentration (IC50) of adriamycin on MCF-7 / ADM was determined by MTT method was detected by RT-PCR (F test) and Western Blot (F test) respectively. Results: After 24 h treatment of SB203580, the apoptosis rate of MCF-7 / ADM was 26.73 ± 4.90% higher than that of the control group and untreated group = 143.80, P <0.001). The sensitity to the ADM was improved significantly (F = 148927.1, P <0.001), and the reversal effect of treat SB203580 group was 68.45%. The P38MAPK protein (F = 685.419, and MDR-1 mRNA expression after SB203580 24 h action were lower than the control group and untreated group (F = 9139.24, P <0.001). Conclusion: P38MAPK signal way plays an important role in drug resistance of breast carcinoma cell. p38MAPK can protect MCF-7 / ADM cells from apoptosis, and blocking the p38MAPK signal way can increase the apoptosis for breast carcinoma drug resistance cell lines.