Scores from two versions of the Clinical Institute Withdrawal Assessment for Alcohol, the CIWA-Ar and CIWA-AD, were compared in 135 alcohol detoxification episodes. The paired mean score for withdrawal severity was statistically higher with the CIWA-AD (p < 0.001), but the mean difference of 0.45 (95% CI: 0.38-0.53, t = 11.74) is not likely to be clinically significant. The difference in the total score between the two scales was 1 point or less 82.6% of the time, and nearly all (97.7%) of the CIWA-AD scores were within 3 points of the paired CIWA-Ar score (range - 6 to + 6).