A total of 40 plant extracts traditionally used by the Alteños Indians, a native community living between the Andean block and the tropical valleys of Bolivia, were screened for antimalarial activity in vitro on Plasmodium falciparum chloroquine resistant (Indo) strain, and in vivo on rodent malaria Plasmodium vinckei petteri. Eleven extracts displayed good or moderate activity in vivo, and ten extracts good or very good antimalarial activity in vitro. Results of the screening are discussed here, in relation with the traditional use of plants.