AbstractBackgroundYouth with bipolar disorder (BD) are at greatly elevated risk for suicide. Self‐harm, encompassing all self‐injurious behaviors regardless of suicidal intent, is among one of the greatest risk factors for death by suicide. This study aims to extend the sparse literature regarding the neurostructural correlates of self‐harm in youth with BD.MethodsParticipants included 156 youth (17.14 ± 1.61 years): 38 BD with lifetime history of self‐harm (BD_SH+), 43 BD without history of self‐harm (BD_SH−), and 75 healthy controls (HC). Measures of cortical thickness, surface area (SA), and volume were obtained using 3 T magnetic resonance imaging. Orbitofrontal and ventrolateral prefrontal cortices were examined in region‐of‐interest (ROI) analyses, complemented by exploratory vertex‐wise analyses using a general linear model controlling for age, sex, and intracranial volume.ResultsIn ROI analyses, there were no between‐group differences after correction for multiple comparisons. Vertex‐wise analysis revealed three significant clusters in precentral gyrus SA, inferior temporal gyrus SA, and caudal middle frontal gyrus volume. Post‐hoc vertex‐wise analyses showed BD_SH+ had lower cortical SA and volume compared with both BD_SH− and HC for all clusters.ConclusionsSignificant vertex‐wise findings were observed in frontotemporal regions relevant to BD and self‐harm, with smaller neurostructural measures among BD_SH+ compared with both BD_SH− and HC. Future studies are needed to evaluate the temporal nature of the relationship of these neurostructural differences (i.e., potential risk indicators) to self‐harm and to identify mechanisms underlying these findings.