In this study, we sought to determine whether the risk of failure of coil occlusion of patent ductus arteriosus (PDA) could be predicted on the basis of echocardiographic variables. The echocardiographic characteristics of patients in whom PDA coil occlusion failed were compared with those in whom the procedure was successful. A total of 5 variables were evaluated: PDA diameter (PDAd); indexed PDAd; PDA shape; left ventricular end-diastolic diameter; and the presence of flow reversal in the descending aorta. We found that 2 variables related to the size of the duct (PDAd and PDAd/body surface area), and 2 related to the magnitude of the shunt (left ventricular end-diastolic diameter and flow reversal) were positively associated with failure (P < .05). PDAd and flow reversal had the greater effect in each group and remained significant when they were put into a logistic regression model to predict failure (P = .004 and .053, respectively). In conclusion, echocardiographic variables can predict risk of failure in patients undergoing PDA coil occlusion.