Using data from 33 European countries (including all EU member states), this study aimed to 1) estimate the prevalence of unrecorded alcohol use among past-week alcohol users, 2) describe how unrecorded alcohol use is associated with drinking patterns, and 3) estimate the contribution of unrecorded alcohol to the total amount of alcohol consumed annually in these countries. Data from 25,728 adults who drank alcohol in the past week and self-reported their use of unrecorded alcohol in 2021 were analysed. Prevalence of unrecorded alcohol use in the last week was estimated for those with low, medium, and high risk drinking categorised using the WHO-recommended risk thresholds and definition of risky single occasion drinking. Prevalence estimates were weighted for the country-specific gender, age, and geographical population distribution. An adjusted weighted proportion of unrecorded drinking occasions in total drinking occasions was calculated and compared to 2020 recorded annual per capita consumption estimates. Among past-week alcohol users, the average prevalence of past-week unrecorded alcohol use was 12.1% (95% CI: 11.7-12.5%), with considerable difference between countries (min: 2.0% in Malta; max: 27.0% in Greece). Unrecorded alcohol use was much more prevalent among people with high-risk alcohol use in the past week (24.2%, 95% confidence interval [CI]: 22.9-25.5%) compared to people with low- (6.5, 95% CI: 6.0-6.9%) or medium-risk alcohol intake in the past week (13.6%, 95% CI: 12.9-14.3%). Unrecorded alcohol accounted for 7% of per capita consumption in 2020. This is the first comparable assessment of unrecorded alcohol use across EU and affiliated countries. The findings add support to the observation that availability of unrecorded alcohol may contribute torisky drinking in Europe. The observed country variations may be related to differences in country-specific pricing policies and measures to reduce the production and consumption of unrecorded alcoholic beverages.