This study assessed the reliability, validity, discriminative accuracy, and factor structure of the Detoxification Fear Survey Schedule (DFSS). Prevalence of detoxification fear and its correlates also were assessed. Random samples from three geographically, culturally, and racially disparate populations (N = 271) of treated opioid addicts were used. The DFSS had a test-retest r = .935 and demonstrated several indicants of validity. A briefer version (DFSS-14) showed superior psychometric properties and could identify correctly 81% of detox fear subjects while it excluded 55% of nonfear subjects. The DFSS-14 had a replicated three-factor structure that accounted for 62.1 Yo of total item variance in the validation sample. Factor two, probably best named dose reduction fear, was replicated in all populations. A cut-off score set at the nonfear mean is recommended for clinical use. A brief clinical interview of positive scorers quickly should eliminate false positives and, thus, efficiently identify most of those with detoxification fear.Detoxification from methadone is difficult, and successful outcome is the exception. Only 35.7% completed detoxification in Kleber's (1977) review, and Simpson, Joe, and Bracey (1982) reported a 19% completion rate. Successful detoxification from illicit opiates, without a period of methadone maintenance, has been even lower. Wilson, Elms, and Thompson's (1975) review found a total of 19.6% successfully detoxified. Why is detoxification, especially from methadone maintenance, so difficult and success rates so low? One part of the answer lies in the effect of negative emotional reactions to detoxification discovered in recent research.Anxiety about detoxification seemed to exacerbate withdrawal symptoms and caused more patients to abort detoxification (Senay, Dorus, Goldberg, & Thornton, 1977). Anxiety over dose reduction in the absence of withdrawal symptoms during a slow detoxification was one of the main reasons 25% of rehabilitated patients discontinued detox-The authors wish to acknowledge the assistance of Gary Cutter, Ph.D., UAB Department of Biostatistics, who provided valuable consultation for data analysis strategies and methods. We also wish to acknowledge the staff at each of the three clinics: UAB, Sepulveda, and Philadelphia. Nurses, receptionists, and counselors were extremely helpful in introducing interviewers to subjects and enlisting support and cooperation, for which we are extremely grateful.