Introduction: Of the domains assessed by the CIWA-Ar, tremor is the most objective, and reliable clinical symptom of alcohol withdrawal syndrome. Even so, anecdotal evidence suggests that the ability of health care workers to reliably rate tremor severity is highly variable, and there is no high quality, readily available training to teach this competency. Improper evaluation and interpretation of tremor may result in under or over treatment, posing serious risks to patient safety, prolonging emergency department (ED) length of stay, and increasing the likelihood of complications/hospital admission. The objective of this study was to prospectively compare tremor assessment scores assigned by nurses and clinical experts for patients with alcohol withdrawal syndrome in the ED. Methods: A prospective observational study was conducted for patients ≥18 years presenting to an academic ED in alcohol withdrawal from Oct 2014 to Aug 2015. Individual tremor assessments were videotaped by a research assistant and subsequently reviewed by 3 clinical experts, blinded to the primary clinical assessment. Tremor severity was scored using the 8-point CIWA scale (0=no tremor, 7=severe tremor). Tremor severity scores assigned in real-time by the nurses were compared to expert assessments of each video. Inter-rater agreement was estimated using Cohen’s kappa (k) statistic. Results: 31 patients with 62 tremor recordings were included. Nurse-derived tremor scores matched exactly with expert assessor scores in 11 (17.7%) cases, within 1 point for 29 (46.8%) cases and differed by ≥ 2 points in 33 (53.3%) cases. The overall kappa for agreement within 1 point for tremor severity was ‘fair’ 0.39 (95% CI: 0.25, 0.53). Conclusion: These results confirm the high variability in the assessment of alcohol withdrawal tremor by health care workers. Future research should focus on ways to improve the accuracy of tremor in alcohol withdrawal patients, and the development and implementation of an educational program to improve the individual competencies of clinical staff in the recognition and treatment of alcohol withdrawal in the ED.