Precarium settling is not a recent problem, however, in Costa Rica this phenomena has worsen during the last fifteen years.  The aim of this review is to improve the knowledge about precarious settling in Costa Rica and to suggest a possible impact in human health.  Precarious settlings are consider part of the general deterioration in housing conditions in Latin America, where three quarter parts of its population llve in few big cities.  Due to the urgent need to establish international mechanisms to collect and publish information about the effects of human establishment and housing on the health, this work analyze the origins of precarious settiings since ancient ages until present within the context of social and economical factors.  We stress the importance of poverty as a cause of precarious establishments in Latin America.  An historical analysis about the problem of slum in Costa Rica is performed, showing an increase in frequency since 1980 specially in the West side of the Capital, been the Pavas District more affected.  Demographic figures about the precarious establishment Villa Libertad are shown.

Precarious settlings; slum; poverty; Villa Libertad; Pavas