An epidemiological servey for malaria was conducted in the municipality of Ariquemes, Rondonia, Brazil. Blood smears were taken to detect malaria parasite and a questionaire was employed to obtain information on the populations knowlege of the causes and treatment of malaria and determine the importance of dislocations of people on the transmission of malaria. The surveu population of 936 famílias included 4.633 people, representing 8% of the population of the Ariquemes County. Of 2.310 people surveyed in the urban area malaria infection was detected in 68 being 69% P. falciparum and 31% P. vivax. In the 2.323 people studied in the rural area 151 malaria infections where detected with 53% being due to P. falciparum and 47% P. vivax. The infection was more prevalent in men than women in both rural and urban areas. In the rural area the 6 - 14 year age group had the highest prevalence with th 15 - 29 age group being the most affected in the urban area. All malaria infections were treated following standard SUCAM procedures, as recommended by, the world Health Organization. The internal migrations within the survey area were responsible for many of the urban cases of malaria, being imported from the rural area. Nearly 50% of the population did not know that the mosquito was involved in the malaria transmission. The majority of the survey population were either illiterate or only had primary education. Almost 90% of these peopel came form other Brazilian States, mainly from the South of Brazil.