This thesis investigates Endomyocardial Fibrosis (EMF), the commonest form of restrictive cardiomyopathy affecting children and young adults from poor developing countries. EMF is the second cause of admission for acquired cardiovascular disease in these age groups in endemic areas and has an unclear etiology and pathogenesis. It has no specific treatment and carries a poor prognosis. The methodology followed for this investigation was the implementaion of large-scale epidemiological studies on incidence, prevalence and determinants of EMF in an endemic area of Mozambique, using echocardiography. New classification and scoring system for diagnosing and assessing EMF severity was evolved and applied in community and hospital-based studies. Concomitantly, characterization of the clinical and biological profile of EMF in its different stages was done, as well as investigation of the genetic susceptibility to the disease. Finally, new surgical procedures based on the specific pathophysiology were developed and applied, with attempts at optimizing the timing of surgery and its results. This work has established that echocardiographic screening is able to detect early and asymptomatic stages of EMF, and that it is a useful tool in assessing its progression, identifying patients that can benefit from surgery and monitoring response to treatment. It also shows that novel surgical approaches based in tailored techniques to the specific components of the disease can improve the outcome. The use of the standardized criteria in prospective studies may improve knowledge of the natural history and pathogenesis of EMF allowing better management of EMF and identication of new therapeutic targets.