The government measures heroin supply by assessing the purity of street-bought samples, assuming that general supply will be reflected in the amount combined with neutral agents in retail samples. However, a larger, more representative number of street purchases or seizures is needed to indicate how much heroin is available. Having local police supply the government with street samples has not expanded the data base, and new data criteria are needed to disqualify wholesale samples that do not reflect the street supply. Heroin death and injury statistics, the basis for reports of a decreasing U.S. heroin problem, are supplied by inaccurate data from hospital emergency rooms and medical examiners. Recent studies have found that many cases of heroin abuse go unreported. Using heroin seizures by Federal or other law enforcement agents to assess how much the government interferes with the heroin supply is hindered by poor reporting methods that allow more than one seizing agent to report the same seizure. A sample report shows that at least 114 of 249 pounds seized in 1976 were reported twice. In addition, estimates of the numbers of heroin addicts are made with questionable methods, and heroin indicators in general are cited in many government publications without sufficient qualification, thereby being misleading. An appendix describes how heroin causes death.