The evidence suggests that limited health literacy (HL) may be associated with health risk behaviour such as smoking, alcohol drinking, or substance use. The aim of this study was to examine the level of HL in people undergoing treatment for alcohol abuse and to determine the most problematic domain of HL. The cross-sectional survey included 113 participants from two facilities in Prague (Department of Addictology and Bohnice Psychiatric Hospital). HL was measured using the HLS-EU-Q questionnaire developed by the European Health Literacy Consortium. The mean general health literacy (GHL) score of the sample was 34.1, indicating a sufficient level of HL. However, almost half of the sample showed a limited level of HL. Health promotion was identified as the most problematic domain of HL, with fifty percent of participants having a limited level. Outpatients achieved overall better scores than inpatients, although the difference was not significant. We found no statistical differences between tested variables. The results suggest that the prevalence of limited HL in people undergoing treatment for alcohol abuse is relatively high. Interventions should be carried out to increase the overall level of HL. An adequate level of HL may improve overall health, as well as the treatment outcomes of people addicted to alcohol.