Background: The causes of childhood leukemia as the most common malignancy in children are vastly unknown.The aim of this study is to evaluate the relationship between maternal birth characteristics with environmentalexposures in childhood leukemia.Methods: This is a case-control study which consists of children younger than 18 years old suffering from leukemiawho reside at Fars Province of Iran. Patients were individually matched with variables such as age, sexand residence region. In order to evaluate the relationships between each variable and the risk of leukemia, oddsratio(OR) and 95% confidence interval (CI) were estimated using conditional logistic regression.Results: Statistically, the association between risk of childhood leukemia with birth order (OR=6.177, 95%CI:2.551-14.957), pet ownership (OR=2.565, 95%CI: 1.352-4.868) and history of leukemia in first and second degreerelatives (OR=2.667, 95%CI: 1.043-6.815) was significant. However, there was no significant associationbetween daycare attendance, history of miscarriage, number of siblings and history of mother's diagnostic radiologytests with risk of childhood leukemia.Conclusion: Although no definite etiologic factor for acute childhood leukemia has been clearly defined, thecontribution of environmental risk factors in the context of genetic predisposition are strongly elucidated.