Polymorphisms have been identified in several DNA repair genes. These polymorphisms may effect DNA repair capacity and modulate cancer Susceptibility. In this Study, we aimed to determine the fool polymorphisms in two DNA repair genes, xeroderma pigmentosum complementation group D (XPD) and X-ray repair cross-complementing group 1 (XRCC1). in a sample Of Turkish patients with childhood acute lymphoblastic leukemia (ALL), and evaluate their association with childhood ALL development. We used polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP), to analyze MID Asp312Asn, MID Lys75IGln, XRCC1 Arg194Trp. and XRCC1 Arg399Gln polymorphisnis in 70 patients with childhood ALL and in 75 disease-free controls, who were of a similar age. No significant differences were observed among the Study groups with regard to the MID codon 312, XPD codon 751. XRCC1 codon 194, and XRCC1 codon 399 polymorphisms. However, the combined XRCC1 Arg194Trp/Trp194Trp variant genotypes were associated with increased risk for-ALL in females(OR=5.47: 95% CI= 1.49-20.10: p=0.008). This finding indicates that females carrying XRM 194Trp allele are at increased risk of developing childhood ALL. These results Suggest that the risk of childhood ALL may be associated with DNA repair mechanisms, and understanding these mechanisms will help identify individuals at increased risk of developing childhood ALL, and also should be lead to improved treatment of ALL. (C) 2008 Elsevier Ltd. All rights reserved.