Purpose: To assess the self-reported Oral Health Related Quality of Life (OHRQoL) among institutionalised patients in an alcoholic detoxification programme in northern Portugal. Materials and Methods: This analytical cross-sectional study using the Oral Health Impact Profile-49 (OHIP-49) was carried out in 300 individuals institutionalised for alcohol detoxification in withdrawal units. The seven OHIP-49 domain scores and three summary indicators were examined: 'Prevalence' (percentage of people reporting one or more of 49 items at least 'fairly often'), 'Extent' (number of impacts [items] reported at least 'fairly often') and 'Severity' (mean sum of the participants' OHIP score). Results: The sample comprised 83.3% males with a mean age of 44 ± 8.6 years and an abusive alcoholic consumption history of 21.2 ± 11.5 years. The results show a 'prevalence' of 62.4% (95% CI: 56.7%-67.7%), the mean 'extent' was 3.8 (95% CI: 3.2-4.5) impacts and the mean 'severity' level was 54.8 (95% CI: 49.9-59.7). 'Prevalence' was significantly and positively associated with patients with gastroesophageal reflux disease (GERD), those with a higher estimated daily alcohol intake, who previously used hashish and who brushed their teeth after drinking alcohol. 'Extent' was higher among females, those with higher levels of education, patients with GERD, smokers, and those with a higher estimated daily alcohol consumption; it was negatively associated with not brushing teeth. 'Severity' was significantly and positively associated with female gender and smoking, and negatively associated with not brushing teeth. Conclusion: This population of alcohol-dependent patients undergoing an addiction rehabilitation programme presented a high prevalence of negative oral health impacts, but not a high extent or severity. Keywords: dental care, oral health, OHIP, OHRQoL, quality of life