After a rash of fatal overdoses among drug users that was attributed to the synthetic narcotic analgesic fentanyl, the New Jersey Department of Health conducted street interviews with 160 injection drug users in an attempt to identify the channels through which this population had heard about the outbreak and to gauge drug addicts' responses to the incident. The results of the investigation suggest that the drug users learn about such severe threats to health from a variety of sources. The frequency with which some of these sources are reported differs significantly according to the sex of the drug user and, even when sex is controlled, the frequency may vary substantially from city to city in a relatively limited geographic area. Although television was, for this population, a more important source of information about the outbreak than was any other formal means of communication, drug users did not regard TV as a reliable source of good information about "bad dope." Moreover, it does not appear that broadcasts of public warning messages about such substances are a guarantee that addicts will not search for the drug. The data reported in this study point up a need for health officials' greater understanding of the channels through which drug users receive information on threats to their health. The study also provides an understanding of how public health messages are perceived and processed by needle users. The final lesson is the need for close collaboration among drug enforcement personnel, testing laboratories, and health officials in the various affected locales to clarify the public health message.