Objective:To observe the effects of hyperthermia on the sensitivity of gastric cancer cell lines to paclitaxel (TAX) . Methods :To establish TAX-resistant gastric cancer cell line through a method of increasing concertration gradient and named it MKN-45/TAX .Immunocytohistochemistry staining method was used to detect the expression of multi-drug resistance gene (MDR1) in MKN-45/TAX and MKN-45 .CCK-8 test was used to detect the proliferation inhibition rates in two kinds of cell lines under different temperatures and different TAX concentration .Real-time polymerase chain reaction (RT-PCR) and West-ern blotting were used to detect the expression of MDR1 mRNA and P-glycoprotein (P-gp) before and after target siRNA treat-ment .Results:Establishment of MKN-45/TAX cell line was successful .The expression level of MDR1 was high in MKN-45/TAX whereas it was low in MKN-45 .As TAX concentration increased ,the proliferation inhibition rates of both cell lines in-creased .At 42 ℃ the proliferation inhibition rate of MKN-45/TAX to TAX chemotherapy decreased ,while that of MKN-45 was the opposite .Both the expression of MDR1 mRNA and P-gp decreased after the siRNA transfection .Conclusions :Hyper-thermia combined with chemotherapy may enhance the resistance of TAX-resistant gastric cancer cell line to TAX ,while it may enhance the sensitivity of TAX-sensitive gastric cancer cell line to TAX .The mechanism may be related to the expression of MDR1 .