Abstract: The present invention relates to the delivery of opioids through an inhalation route. Specifically, it relates to aerosols containing opioids that are used in inhalation therapy. In a composition aspect of the present invention, the aerosol comprises particles comprising at least 5 percent by weight of an opioid. In a method aspect of the present invention, an opioid is delivered to a mammal through an inhalation route. The method comprises: a) heating a composition, wherein the composition comprises at least 5 percent by weight of an opioid, to form a vapor; and, b) allowing the vapor to cool, thereby forming a condensation aerosol comprising particles, which is inhaled by the mammal. In a kit aspect of the present invention, a kit for delivering an opioid through an inhalation route to a mammal is provided which comprises: a) a composition comprising at least 5 percent by weight of an opioid; and, b) a device that forms an opioid aerosol from the composition, for inhalation by the mammal.