Intestinal worm infection, is still high in Indonesia. It is understood because Indonesia is a developing country with low socioeconomic status, knowledge, environmental and personal hygiene. This can support the spread and infection of worms. The highest prevalence and intensity were found in primary school children. In North Sumatera, the prevalence of 57-90% in 1995 was found in Suka village which is located at 1400 meter above sea level with temperatures between 18-22 oC and humidity of 70%.4 The number of primary school children infected was relatively high (648 persons). The population was 3821 people. Many with low income are predicted to be highly infected by intestinal worms. The aim of this study was to determine the prevalence of intestinal worm infection in primary school children and its association with socioeconomic status and other factors such as age, gender, parents' education and parents' occupation.