Some countries allow physicians to prescribe pharmaceutical-grade diamorphine to dependent users who have previously undergone treatment but are still using street-sourced heroin; this is not allowed in the US. This study provides the first nationally representative US data concerning public support for prescribing diamorphine to dependent users. We also test the hypothesis that calling it "diamorphine" instead of "heroin" increases support for this approach. The RAND American Life Panel is a nationally representative, probability-based survey of US adults. Of the 3345 panel members invited to take the survey, 2530 (75.6%) provided a valid response to our question module. Respondents were randomly assigned to have the question refer to the prescribed drug as either "heroin" or "diamorphine." The groups did not significantly differ on sex, age, race/ethnicity, or education. We compare the distribution of responses for the two groups and conduct Pearson's chi-squared test with the Rao-Scott correction. For those asked whether the US should try prescribing pharmaceutical-grade "heroin," the share answering "Yes" (20.8%) was 15 percentage points lower than those responding "No" (35.8%). When the question asked about "diamorphine," the results were nearly reversed: the share answering "Yes" (30.6%) was almost 12 percentage points higher than those responding "No" (18.9%). The distributions of responses were significantly different (p < 0.001). Support for prescribing diamorphine to dependent users is low in the US. While the results are consistent with the hypothesis that referring to heroin as diamorphine may reduce stigma associated with the substance and increase support for prescribing it, opinions may change as individuals learn they are different names for the same substance.