In King County, Washington, during 1985-1986, 98 children aged less than 15 years involved in pedestrian-motor vehicle collisions resulting in death or injuries severe enough to require hospitalization were identified through the Trauma Registry at the Regional Trauma Center and the Medical Examiner's Office. Two age- and sex-matched controls were selected for each case, one through random digit dialing and the other from children undergoing appendectomy. Various environmental and traffic characteristics were ascertained from visits to the neighborhoods of all subjects. Children living in multifamily dwellings had a risk for injury that was 5.5 times greater than children living in single family homes (95% confidence interval 2.5-12.3). In general, areas with busier streets (greater posted vehicle speeds and/or greater traffic volumes) were associated with increased risk for pedestrian injuries. The lack of pedestrian crossing devices, crosswalks, or sidewalks, however, was not associated with an increased risk. When the analysis was restricted to the 23 cases injured in front of their homes and their controls, risks were not elevated for any of the street or traffic characteristics. The small size of the study and the lack of relevant information for many subjects limited our ability to adjust for the likely confounding influence of other household/environmental factors. Thus, these results should be viewed as suggestions for future investigations of the causes of childhood pedestrian injuries.