Rotavirus gastroenteritis (RVGE), a vaccine preventable disease, remains a common cause of severe gastroenteritis in children globally. Ireland introduced the universal rotavirus vaccination to the national immunisation programme in 2016. In this paper the economic impact on RVGE related hospitalisations amongst children under 5 years is examined. Using national data from all Irish public hospitals, an Interrupted Times Series Analysis (ITSA) compares RVGE hospitalisations amongst children under 5 years, pre- and post-vaccine introduction. Costs are estimated and ITSA results are compared to the counterfactual to estimate the economic impact of the vaccine. A probit model examines patient characteristics pre- and post-vaccine introduction. Vaccine introduction coincided with lowered RVGE related hospitalisations. While this effect was delayed (1 year) there is evidence of a sustained impact. RVGE patients' post-vaccine introduction were likely to be over 2 years (p = 0.001) and length of stay was lower on average (p = 0.095). The counterfactual analysis revealed 492 RVGE hospitalisations were avoided on average annually since the introduction of the vaccine. This has an estimated economic value of €0.92 million per annum. Following the introduction of the rotavirus vaccine in Ireland, hospitalisations for RVGE decreased significantly and those hospitalised were older and with a reduced length of stay on average. This has the potential for significant cost savings for the Irish healthcare system.