Between 1981 and 1988, the Minnesota Department of Health actively responded to over 400 reports from persons concerned about disease occurrence in their community, school, or workplace. Almost all of these reports involved perceived excesses of cases of cancer. Although there is little potential for identifying unsuspected public health problems or developing new etiologic insights, the Minnesota Department of Health has found that responding to reported clusters is a legitimate and necessary public health activity. To be responsibly responsive to these concerns, the Department has developed four steps to prioritize investigation of reported disease clusters, as well as six criteria for determination of the feasibility of environmental epidemiologic investigations. Approximately 95% of all concerns have been handled within the first two steps of this approach, generally requiring only education, or sometimes examination of readily-available data. Less than 5% of the concerns have required additional data collection and evaluation, and only about 1% have resulted in full-scale epidemiologic studies. Successful conclusions at all levels of this process require that public health officials develop effective communication, maintain objectivity, and provide leadership for controversial and difficult issues.