Acute lymphoblastic leukemia (ALL) is the most common pediatric caner. (XRCC1) plays an important role in base excision and single-strand break repair, as a scaffold protein that brings together proteins of the DNA repair complex, and appears to be a candidate for cancer risk. However, studies on the association between polymorphisms in this protein and cancer have yielded conflicting results Genetic polymorphisms in this gene may contribute to the susceptibility to childhood ALL .The most common 3 polymorphisms are at codon 194 (Arg) to (Trp) (Arg194Trp), at codon 280 (Arg280His) and at codon 399 (Gln) (Arg399Gln).. We studied their effect on 30 ALL patients and 30 healthy controls regarding the incidence, toxicity and response to treatment using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). codon 194 Trp genetypes were found to contribute a significantly increased risk of ALL by 15 fold (OR=15.5, 95%CI=3.8-63.4,P-value<0.0001).Treatment toxicity with codon 399 polymorphism showed a favorable outcome than wild type (p-value 0.04).