Objective: To determine the occurrence and severity of dental erosion in alcoholic patients undergoing detoxification at the North Alcoholic Regional Centre (CRAN), Porto, Portugal, and to assess socioeconomic and behavioural covariates of dental erosion occurrence. Design: A cross-sectional descriptive study was carried out in one centre (CRAN) for addiction rehabilitation therapy in the north of Portugal. A sample of 1064 teeth was examined.The condition of the dental erosion was classified by means of severity and anatomic location, according to the Eccles and Jenkins dental erosion index, and a dichotomous outcome assessing the occurrence of dental erosion (severity dental erosion levels > 0 ). Dental erosion results were linked to data supplied by a questionnaire assessing socio-demographic characteristics, behaviour related to alcohol and drug use, including a history of drug and alcohol abuse, and oral health promotion using logistic multivariate regression analysis. Results: Enamel and/or dentine erosion lesions were present on 49.4% of the teeth. Among these, 36.9% of occlusal surfaces presented dental erosion with a severity level of 1, 11.4% with a severity level 2 and 1.1% with a severity level 3.The highest occurrence of severity level 3 was found to exist in palatal dental surfaces (1.9%). Dental erosion on teeth surfaces was found to be independently associated with intra oral location (by arch, tooth type), patients’ socio-demographic characteristics, behaviour associated with a history of alcohol and drug abuse, and oral health promotion. Maxillary teeth, more so than mandibular teeth, presented moderate to higher severity erosion injuries (Wilcoxon test; p< 0.001); and significant differences in the severity of dental erosion were found between anterior and posterior teeth, in both the maxillary and the mandibular arches (Friedman test, p< 0.001). Conclusions:Alcohol-dependent patients undergoing a detoxification programme presented a high occurrence and a low severity of dental erosion lesions.The palatal surfaces of the anterior teeth, followed by incisive/occlusal surfaces in both anterior and posterior teeth, respectively, were most affected by erosion injuries