Background: Multidrug resistance is the main reason for unsuccessful chemotherapy. The important reason of drug resistance is ATP dependent pumps shus as MDR1 that extrude drugs from the cell. MDR1 is high polymorphic. It seems that polymorphisms influent on gene expression and response to treatment. The aim of this study was investigation of C1236T polymorphism MDR1 gene and it’s association with response of treatment in childhood acute lymphoblastic leukemia.

Materials and Methods: In this descriptive study, C1236T polymorphism of MDR1 was investigated in 44 acute lymphoblastic leukemia childhood and 40 healthy individual by ARMS-PCR technique. Association of this polymorphism with response to treatment was also investigated. Data were analyzed using Chi-squre test and SPSS software. P values <0.05 were considered to be statistically significant.

Results: There was no significant difference in frequencies of C1236T polymorphism between patients and healthy group (p=0.876). Frequency of C1236T polymorphism of MDR1 between responder and non responder was not significant (p=0.304).

Conclusion: It seems that there is no correlation between C1236T polymorphism of MDR1 gene and response to treatment. So the role of C1236T polymorphism in gene expression MDR1 in childhood acute lymphoblastic leukemia and response to treatment is still controversial.