Postmortem heart specimens are essential for education and research on the anatomy, morphology, and pathology of congenital heart defects. However, such specimens are rarely obtained these days, and the specimens stored in formalin are inexorably deteriorating. This study aimed to develop methods to archive three-dimensional data of rare human heart specimens and to publish the data. All wax-infiltrated human postmortem heart specimens stored in the Cardiac Registry, Boston Children's Hospital were scanned using microfocus computed tomography (X-Tek HMXST225, Nikon Metrology, Inc.), and reproduced using a three-dimensional printer (Form 3B, Formlabs Inc.). The digital models were published as an interactive three-dimensional online atlas. The resolution of the three-dimensional data was evaluated. The primary diagnoses in the 88 specimens included in the study include normal cardiac anatomy (11 cases), transposition of the great arteries {S,D,D} (11 cases), ventricular septal defect (10 cases), double-outlet right ventricle (9 cases), hypoplastic left heart syndrome (9 cases), and common atrioventricular canal (7 cases). Twenty-five cases (28%) underwent previous surgical or percutaneous interventions to the heart, including Mustard procedure (1 case), Senning procedure (2 cases, one was performed on a postmortem heart specimen). The median voxel size of the three-dimensional data was 40.5 um (IQR, 32.8-64.2). All intracardiac structures were precisely reproduced as digital and physical three-dimensional models. The methods and resultant models were considered useful for archiving and furthering the utilization of these invaluable specimens. The atlas is available at https://www.sketchfab.com/heartmodels/collections.