Background: Vitamin D regulates many aspects of cellular growth and differentiation in normal and cancer cells. There is growing evidence for both serum vitamin D level and VDR gene polymorphism as prognostic factors in hematologic malignancies. Aim of this work: Evaluation of vitamin D serum level and VDR FOKI polymorphism as prognostic factors in adult AML patients. Patients & Methods: Eighty subjects were included in this study, 50 adult patients with newly diagnosed AML and 30 apparently healthy controls matched for age and sex. Venous blood samples were withdrawn from all subjects for measurement of serum 25(OH) vitamin D using competitive photo chemiluminescence and molecular detection of VDR (FOKI) polymorphism, which was done by RFLP PCR. All patients received the standard induction chemotherapy regimen 3 & 7. Results: The rate of vitamin D insufficiency was significantly higher in AML patients compared to controls (58% vs 16%, p = 0.03). The mutant FOKI genotype (FF & Ff) was found in 52 % of patients compared to 23 % of controls (p = 0.02). Patient with sufficient vitamin D level showed a significantly higher complete response rate compared to those with insufficient level (90% vs 44%, p = 0.02), while none of the other clinical features showed significant relation. Patients with wild type FOKI polymorphism (FF) were more likely to have favorable cytogenetics, while patient with mutant FOKI polymorphism were more likely to have poor cytogenetics (p = 0.03). The CR rate was highest in the wild type FF group (87.5%) followed by the heterozygous Ff group (50%), while none of the patients in the homozygous ff group achieved CR (p = 0.04). Conclusion: VDR FOKI polymorphism and serum vitamin D level showed a significant impact on the treatment outcome of adult AML patients suggesting their potential role as prognostic factors in these patients. Longer follow up will be needed to study the impact on overall and disease free survival.