Disorders of the right intraventricular conduction were analyzed in cases of chronic pulmonary hypertensive cardiopathy (C.P.H.C.), diagnosed on basis of the anatomic data. The series studied here (40 cases) was obtained from the review of 3,000 reports of autopsies at the Instituto Nacional de Cardiología de México. Thickness of the free right ventricular wall, thickness of the interventricular septum at three levels, thickness of Wolf's spur and the circumference of the 4 valvular rings, were determined in each heart. Haemodynamic studies and respiratory function tests were revised in those cases in which they had been practiced. Electrocardiographic study essentially analyzes the time of onset of intrinsicoid deflection as well as the morphology of ventricular complexes in the unipolar leads. In 37 cases (92.5%), a disturbance of the right intraventricular conduction was present. R.B.B.B. was observed in 29 cases (72.5%): 12 of minor degree, 19 of intermediate and 1 of advanced degree. Right peripheral block was diagnosed in 8 cases (20%): anterior type in 2 cases (5%); posterior type in 6 cases (15%). In the cases with R.B.B.B., the anatomic data of right ventricular hypertrophy were predominant; in those with R.A.S.B., anatomical data suggested right ventricular enlargement. The facts exposed here permit the following conclusions: 1) Diagnosis of right fascicular block can be suggested even in the presence of hypertrophy of the corresponding ventricle. 2) Hypertrophy of the right ventricle appears more directly related to the homolateral bundle branch block than to distal or segmentary blocks. 3) Topographic diagnosis of delay in the right ventricle activation process can be established by an electrocardiographic thoracic mapping that permits to explore the ventricular structures at different levels.