Background: Kawasaki Disease (KD) is considered a major acquired heart disease in children under the age of 5. Coronary artery aneurysm (CAA) can occur in serious cases despite extreme therapy efforts. Previous studies have reported low serum albumin level was associated with disease outcome, but no further investigation was addressed yet. Method: This retrospective (case-control) study randomly included children with KD who were admitted and underwent laboratory tests before undergoing IVIG treatment in this institution, the largest tertiary medical center in southern Taiwan from 2012-2016. Prognostic nutrition index (PNI), an albumin-based formula product, was evaluated as a predictor of CAA the first time. The progression of CAA was monitored using serial echocardiography for six months. We performed multivariable logistic regression analysis on the laboratory test and PNI with the disease outcome of the KD patients. Result: Of the 275 children, 149 had CAA, including transient dilatation, while the other 126 did not develop CAA during the 6-month follow-up period. A multivariate logistic regression model revealed that PNI, gender, IVIG non-responder, and platelet count are significant predictors of CAA with a 95% confidence interval estimator of 1.999, 3.058, 3.864 and1.004, respectively. Using PNI to predict CAA presence gave an area under the receiver-operating-characteristics (ROC) curve of 0.596. For a cutoff of 0.5 in the logistic regression model and the PNI cut-off point is taken as 55 together with IVIG non-responder, boy gender, and platelet count take into account, sensitivity and specificity were 65.7% and 70.4%. Conclusion: PNI could be a candidate of adjunctive predictor of coronary artery aneurysm in addition to IVIG non-responder. Together with low PNI, IVIG non-responder, male gender and platelet count will give high odds to predict coronary artery aneurysm within 6 months of illness.