Abstract： Objective To study the expression,co-expression, and clinical significance of four multi-drug resistance factors in lung cancer. Methods The P-glycoprotein (P-gp), mullidrug resistance-associated protein ( MRP, lung resistance protein ( LRP), glutathione-S-transferase (GST-π) of 60 lung cancer patients were detected by immunohistochemical methods. Results The positive drug resistance rate of P-gp, MRP, LRP, GST-π was 53.3% (32/60) ,63.3% (38/60) ,70.0% (42/60) ,80.0% (48/60) respectively. Patients with NSCLC had significantly higher expression of the drug resistance factors than those with SCLC. No relation was observed among the expression of drug resistance factors and TNM stage and cell differentiation. The-expression rate was as follows: Pgp + MRP :41.6%, P-gp + LRP :35.0%, MRP + LRP :53.3%, MRP + GST-π:50.0%, LRP + GST-π: 58.3%, Pgp + GST-π:45.0%. P-gp + MRP + LRP + GST-π:20.0%. Among them, significant relation was detected between P-gp and MRP ( rs = 0.756, P ＜ 0. 0 ), between P-gp and LRP ( rs = 0.689, P ＜ 0.01 ), between MRP and LRP (rs = 0.669, P ＜ 0.01 ), between MRP and GST-π( rs = 0.546, P ＜ 0.01 ), between LRP and GST-π ( rs = 0.848, P ＜0.01 ), between P-gp and LRP( rs =0.535 ,P ＜0.01 ). Conclusions The Multi-drug resistance in lung cancer patients is affected by various multidrug resistance factors. The drug resistance factors' expression is related to histology, but not to TNM stage end cell differentiation.