To determine the prognostic effect of hypertension at diagnosis on outcomes of children with Wilms tumor (WT). Methods: A single center retrospective analysis was conducted on 85 consecutive children with WT diagnosed between January 2000 and August 2013. Patients were classified as hypertensive or normotensive at diagnosis. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method. Cox regression was used to determine the predictive significance of hypertension and other clinical factors. Results: Seventy-one patients had complete data. Of this, 25 (35.2%) were hypertensive and 46 (64.8%) normotensive with corresponding remission rates of 56.0% versus 82.6%, p=0.032; and death as first event of 7% versus 0%, p=0.004. The 5-year OS in the hypertensive versus normotensive patients were (67.1±10.3% versus 89.6±4.9%, p=0.009) and the corresponding 5-year PFS were (53.4±10.4% versus 79.1±6.2%, p=0.007). With univariate analysis, hypertension and local stage were predictors of OS (p=0.012 and p=0.029) and PFS (p=0.030 and p=0.008). In the multivariate analysis, hypertension, local stage, and histopathology were identified as independent prognostic factors of OS (p=0.004, p=0.034, and p=0.038); and hypertension and local stage as prognostic for PFS (p=0.010 and p=0.012). Conclusion: Hypertension at diagnosis is a prognostic predictor of poor outcome in WT and may signify tumor resistance.