Objective. To identify the risk factors for upper urinary tract deterioration in a retrospective study of patients with myelodysplasia. Patients and methods. The medical history, radiographic studies and urodynamic results from 39 children with myelodysplasia who were treated at our hospital were reviewed retrospectively to obtain more accurate data in the prognosis of such patients. The upper urinary tracts were assessed by cysto-urethrography and excretory urography to determine the incidence of vesico-ureteric reflux (VUR) and hydronephrosis. The relationships between the urodynamic variables, including vesical compliance, detrusor hyper-reflexia, detrusor-sphincter dyssynergia (DSD) and the maximum urethral closing pressure (MUCP) to such upper tract deterioration were evaluated using both univariate and multiple logistic regression analysis. Results. The univariate analysis showed low vesical compliance, a high level of MUCP and the presence of DSD to be significant factors for the incidence of VUR. Low vesical compliance and a high level of MUCP also correlated with the incidence of hydronephrosis. The multivariate analysis showed a significant relationship between urodynamic values and upper urinary tract deterioration. The incidence of VUR was strongly correlated with a high MUCP and the presence of DSD. A high MUCP was also a significant factor in the incidence of hydronephrosis. Conclusion. Urodynamic results associated directly with tile abnormal function of urethral control are significantly correlated with the cause of upper tract deterioration in patients with myelodysplasia.