<span name="style_bold">Introduction: </span>Congenital cardiovascular anomalies constitute one of the largest groups among severe congenital defects and exert an important impact over mortality. This study explored the prevalence and tendencies of congenital cardiovascular defects in Costa Rica between the years of 1996 and 2004. <span name="style_bold">Methods: </span>A retrospective population based investigation was undertaken from data of the National Registry of Congenital Malformations, taking into account the following factors: type of cardiac anomaly, maternal age, year of registry and geographic distribution of the patients at birth. Besides, we analyzed the impact of a congenital cardiac defect over infant mortality. <span name="style_bold">Results: </span>The prevalence of congenital heart defects increased from 0,1% to 0,18% during the study period. They exerted greatest impact over infant mortality when compared with any other group of congenital malformations. They show higher frequency in males (p&gt;0.1) and maternal age did not constitute a significant risk factor. The most common lesion detected was ventricular septal defect, finding that agrees with that of other studies from around the world. San José and Limón were the provinces with the highest rates of occurrence and Guanacaste showed the lowest one. <span name="style_bold">Conclusions: </span>In Costa Rica congenital heart defects have become the malformation with the greatest impact upon infant mortality. This finding represents an important challenge to improve their perinatal diagnosis and their registry with the aim of implementing prevention policies.In Costa Rica congenital heart defects have become the malformation with the greatest impact upon infant mortality. This finding represents an important challenge to improve their perinatal diagnosis and their registry with the aim of implementing prevention policies.

Ventricular septal defect; isolated muscular; perimembranous; septal aneurysm