The various terms and classifications of ventricular septal defects (VSD) stimulated us to perform the present study with the purpose of adopting a common terminology and classification in which morphologic, topographic and surgical criteria concur. One hundred and one VSD where studied by means of the sequential segmental approach from the pathologic collection of the Instituto Nacional de Cardiología "Ignacio Chávez". The ventricular septum (VS) was divided in four areas, three muscular (inlet, trabecular and outlet) and one perimembranous. The VSD where described and cathegorized according to their tissue borders, localization and relationship with the cardiac valves and the conduction tissue. The results were: Perimembranous type (77 = 77.23%), with the subtypes according to the muscular extensions: inlet (31 = 39.75%), inlet and trabecular (25 = 32.05%), with three extensions (17 = 21.80%), inlet and outlet (2 = 2.56%), outlet (1 = 1.28%), trabecular (1 = 1.28%), trabecular and outlet (1 = 1.28%); trabecular (9 = 8.91%), outlet (7 = 6.93%), inlet (3 = 3.97%) and mixed types (4 = 3.96%). The topographic-structural classification permits the localization of VSD, as well as to specify their border's tissue and their relationship with the cardiac valves and conduction system. Knowledge of the surgical anatomy of VSD is useful to the surgeon, and constitutes the basis to interpret with precision the diagnostic imaging studies. Delay in the development of the embryonic primordia of the VS and the absence of septal consolidation are the pathogenic mechanisms involved.