Methadone maintenance therapy is an effective treatment for opiate dependence, but more than three-quarters of persons receiving the treatment report sleep quality disturbances. In this double-blind, randomized, controlled trial, we recruited 90 individuals receiving methadone for at least one month who reported sleep disturbances and had Pittsburgh Sleep Quality Index (PSQI) scores > 5. The purpose of this study was to determine whether Suan Zao Ren Tang, one of the most commonly prescribed traditional Chinese medications for treatment of insomnia, improves subjective sleep among methadone-maintained persons with disturbed sleep quality.