SummaryOur objectives were to assess the prevalence of intestinal parasitic infections in Riyadh and to determine associated sociodemographic and environmental factors. The study was conducted through a household survey. Three health centres were chosen from each of the ®ve Riyadh urban regions and 15 from rural areas. Based on the average family size, a random sample of households were chosen. All household members were asked to participate in the study. Data were collected using a pre-designed questionnaire eliciting data on sociodemographic and environmental factors. A stool specimen of each individual was examined microscopically for the presence of trophozoites and cysts.