Exposure to environmental tobacco smoke (ETS) was assessed as part of a pilot study aimed at determining the extent of multiple toxicant exposures in children from inner-city areas of Baltimore, MD. Questionnaire data on sources of ETS and urinary cotinine were obtained in children considered at high risk for urban exposures because of previous or current overexposure to one inner-city environmental hazard, lead. Fifty-three (67.1%) of the 79 participants were exposed to ETS in the preceding 48 h as assessed by questionnaire. Cotinine was present in 77 (98.7%) of the 78 samples assayed with a mean of 79.2 ng/mg creatinine (54.7 ng/ml). Eighty % of children had cotinine values > or = 30 ng/mg creatinine, a level commonly associated with household ETS exposure. Levels in children without reported ETS exposure in their homes were also elevated (mean = 45.0 ng/mg creatinine). As expected, blood lead levels were elevated with a mean of 23.6 micrograms/dl. We conclude that these inner-city children have substantial exposures to both ETS and lead. Furthermore, the presence of elevated cotinine levels in children without known household exposure suggests that ETS should be considered an urban toxicant as well as an individual residential exposure.