The prevalences and intensities of intestinal helminthic infection among primary schoolchildren were determined in rural and urban communities of the Ife Central local government area, in south-western Nigeria. After the schools in the study area had been stratified into urban and rural, a random sample from each stratum was selected for further study. In each study school, a single fresh stool specimen was obtained from each pupil in randomly selected classes and checked, using a quantitative method (Stoll's dilution egg-count technique), for helminth eggs and larvae. Overall, 366 rural and 383 urban schoolchildren were investigated and 30.0% of them (36.1% of the rural and 24.3% of the urban; P<0.001) were found to be harbouring at least one species of intestinal helminth. The mean intensities of infection, in terms of excreted eggs/g faeces of those infected, were 2371.4 for Ascaris, 1070.6 for hookworm, and 500 for Trichuris. Although the mean intensities of Ascaris infection were significantly lower among the infected rural children than among the infected urban (2025.7 v. 2791.4; P=0.014), the corresponding difference in the hookworm infections did not reach statistical significance (1458 v. 666.7; P=0.063). The means of the log-transformed egg outputs, in eggs/g faeces of those infected, also showed similar trends: a significant difference between the rural and urban Ascaris infections (3.1877 v. 3.3340; P=0.002) but not between the rural and urban hookworm infections (2.9667 v. 2.8027; P=0.453). Intestinal helminthiases still clearly represent a common childhood health problem in the study area, particularly in the rural communities.