This study, conducted in Kisumu District, Kenya, identified important risk factors for infection with intestinal helminths using traditional epidemiological methods. This was combined with a rapid assessment study using qualitative methods, which focused on sanitation practices and local illness perceptions. The multiple logistic regression analysis revealed that the absence of latrines was a significant predictor for hookworm infection with an odds ratio (OR) of 1·9. The analysis also revealed that households without soap had a 2·6 times higher risk of being infected with Ascaris lumbricoides compared with households where soap was available, and that the number of inhabitants living in a household was a significant predictor for infections with hookworms (OR=3.2). Furthermore, the presence of children of 5 years and under in the household was a predictor for infection with A. lumbricoides (OR=2.7), while the absence of this age group was a predictor for hookworm infection (OR=3.8). The qualitative part of the study revealed that people did not consider worms as a serious health threat, but as a nuisance. Among the population, latrines were seen as beneficial because they were believed to prevent disease, to provide privacy and to keep the environment free of faeces. Handwashing was done many times a day but usually not with soap, which was mainly used when bathing or washing the whole body. Many inhabitants in a household or the presence of children of 5 years and under were never mentioned as being a disadvantage, and these elements would therefore be difficult to include in a control strategy. Since the lack of latrines and of soap were identified as risk factors for infection, while latrines, soap and medicine were seen as assets by the population, it is suggested that helminth control interventions should be concentrated within these areas in this particular society.