Hepatitis A infection results in a spectrum of illness from asymptomatic disease to severe fulminant hepatitis. Since 2000, <50 cases have been reported annually in Ireland. We report on an outbreak of hepatitis A associated with a childcare facility(CCF) in 2015 in Ireland. Between January and July 2015, 12 outbreak-associated symptomatic hepatitis A cases were identified, including one delayed, retrospective diagnosis. Seven (58%) cases were adults, eight (67%) were male, six of the adults required hospitalisation. All 12 cases were confirmed on serology and the four cases that were genotyped were identical on phylogenetic analysis. Potential environmental exposures and hygiene practices at the CCF were investigated. Outbreak control measures included the provision of: hepatitis A information, infection prevention advice, hepatitis A vaccination to 554 CCF contacts, and voluntary closure of the CCF for deep-cleaning and staff education. From a healthcare perspective1, outbreak control costs were in excess of €45 000. This outbreak illustrates the considerable adult morbidity that can occur in hepatitis A outbreaks, highlights the challenges in controlling a large CCF-associated outbreak and the importance of early recognition by clinicians of hepatitis A.