The United States (US) and Switzerland are affluent countries with different responses to surges in opioid use disorder (OUD) cases over the last thirty years. The Swiss PROVE trail implemented heroin-assisted treatment (HAT) for OUD alongside other medications for opioid use disorder (MOUD). In contrast, heroin remains highly controlled, HAT is inaccessible, and MOUD programs are generally more restrictive in the US than in Switzerland. We conducted a survey to compare practitioners attitudes toward HAT across sites in both countries. Surveys were distributed electronically for voluntary, uncompensated completion (N = 120) at two mental health delivery sites, Psychiatrische Dienste Graubünden (PDGR) in Graubünden, Switzerland and Montefiore Medical Center (MMC) in the Bronx, NY. The survey instrument included 10 demographic and 19 beliefs questions measuring agreement level with a statement on a 5-point scale. Analysis included 79 PDGR respondents (mean age = 43.2, 59.5% women) and 41 MMC respondents (mean age = 44.7, 63.4% women), and did not show differences in confidence to treat OUD, addictions, and psychiatric disorders. For belief in HAT, Swiss respondents had a significantly more favorable view (b = 0.62) than those in New York (p = 0.00027). This study shows a difference in attitudes toward HAT among demographically similar staff treating OUD patients across sites. The cohorts demonstrate an overall positive attitude toward HAT but a more robust positive attitude was evident in Switzerland. Previously unreported attitude comparisons across sites with dissimilar OUD treatment availability may explain differences in practices and success in reducing harm from this disorder.