To assess the risk of rupture using morphological parameters of mirror posterior communicating artery (PcoA) aneurysms. Methods: We retrospectively analyzed the morphological parameters of 39 pairs of ruptured mirror PcoA aneurysms. We performed conditional univariate and multivariate logistic regression for the following morphological parameters: aneurysm height, width, neck width, size ratio, aspect ratio, bottle/neck factor, height/width ratio, internal carotid artery diameter, daughter sac presence and whether height > width. Multivariate regression analysis was performed on the factors found by univariate analysis to have significant correlation with aneurysm rupture (P<0.05). We used receiver operating characteristics (ROC) and the area under the curve (AUC) to test the predictive accuracy of the independent factors for 434 PcoA aneurysm cases in our database. Results: Presence of a daughter sac (OR=8.852, P=0.024), aneurysm with height > width (OR= 18.250, P=0.011), and aneurysm width (OR=1.645, P=0.024), were independent risk factors for the rupture of PcoA aneurysms. The AUC of these factors were 0.737, 0.761, and 0.686, respectively. Conclusion: Aneurysm width, aneurysm with height > width, and daughter sac presence may be independent risk factors for the rupture of PcoA aneurysms. Among these, daughter sac presence was the most accurate predictor for rupture.