Two new rating scales for measuring the signs and symptoms of opiate withdrawal are presented. The Subjective Opiate Withdrawal Scale (SOWS) contains 16 symptoms whose intensity the patient rates on a scale of 0 (not at all) to 4 (extremely). The Objective Opiate Withdrawal Scale (OOWS) contains 13 physically observable signs, rated present or absent, based on a timed period of observation of the patient by a rater. Opiate abusers admitted to a detoxification ward had significantly higher scores on the SOWS and OOWS before receiving methadone as compared to after receiving methadone for 2 days. Opiate abusers seeking treatment were challenged either with placebo or with 0.4 mg naloxone. Postchallenge SOWS and OOWS scores were significantly higher than prechallenge scores in the naloxone but not the placebo group. We have demonstrated good interrater reliability for the OOWS and good intrasubject reliability over time for both scales in controls and in patients on a methadone maintenance program. These scales are demonstrated to be valid and reliable indicators of the severity of the opiate withdrawal syndrome over a wide range of common signs and symptoms.