Cryptosporidiumis a leading cause of gastroenteritis (cryptosporidiosis), with significant morbidity and mortality worldwide. Irish cryptosporidiosis incidence rates are consistently the highest reported in Europe. A retrospective, longitudinal study of clinicalCryptosporidiumisolates was conducted from 2015 to 2018 in Cork, southern Ireland. Overall, 86.5% of cases were attributed toC. parvum, while the remaining 13.5% were caused byC. hominis. Despite the widespread implications of this protozoan parasite in sporadic and outbreak-related illness in Ireland, the current dearth of species-level epidemiological surveillance and clinical studies needs to be addressed in order to elucidate the national impact of this enteric pathogen.