This report provides a comprehensive overview of activity and outcomes in Critical Care Units (Intensive Care Units (ICUs) and High Dependency Units (HDUs)) in adult Health Service Executive funded (HSE-funded, public) hospitals in 2020. Units were heterogeneous in size and case mix, as would be expected from the varying hospitals and specialty profiles they support. Reassuringly, outcomes were relatively consistent across all Units, with almost no outliers for any of the outcome measures reviewed. Outcomes were similar to those observed for the same metrics in United Kingdom (UK) hospitals.