Both pre-clinical and clinical studies make feasible the use of vaccines as novel therapeutic medications to treat drug addiction. No reports to date have shown the development of structural models of opiate candidate vaccines for treating human addiction to such compounds. Here we report on the initial development of a novel structural formulation of a bi-valent vaccine against morphine/heroin. This vaccine was able to trigger and establish a high titer antibody response to haptenized drug with antibodies displaying equivalent specificities for both morphine and heroin. Such antibodies did not cross-recognize structurally dissimilar opiate medications. Furthermore, the evaluation of the potential therapeutic effectiveness of this vaccine was targeted to relapse prevention using a schedule of heroin delivery in the rat self-administration model. Antibodies against heroin blocked its reinforcing effects in rodents. The type of carrier protein used in this vaccine allows further evaluation of its potential therapeutic value for preventing relapse to heroin addiction in humans.