To know the morphological features and the frequency of pulmonary anomalous connection types, 106 hearts from the collection of the Instituto Nacional de Cardiologia Ignacio Chávez were studied with the segmental sequential system. The atrial situs, connections of cardiac segments, morphology of cardiac chambers, interatrial septum, venous collector, sites of anomalous pulmonary venous connection and associated anomalies were determined. Darling's classification was used. The atrial situs was: solitus (73), dextroisomerism (30) and inversus (3). In the supradiaphragmatic level the supracardiac connection (44) was distributed into superior vena cava (24) and vertical vein (20). The cardiac level (39) was divided into venous coronary sinus (22) and to the right atrium (17). The infradiaphragmatic level was to the portal vein (10) and the mixed group (13) had different combinations. 100 hearts had atrial septal defect and 6 had patent foramen ovale. The hearts with dextroisomerism had several intracardiac malformations; 14 specimens had obstructed venous collectors. Three important aspects in diagnosis are: site of anomalous connection, size of atrial septal defect and obstruction in the venous collector; this information is valuable to understand the physiopathology, to establish the diagnosis and to help the surgeon to chose the best surgical strategy.