A collection of three hundred thirty rotavirus-positive stool samples from children with diarrhea in the southern and eastern regions of Ireland between 1997 and 1999 were submitted to the Molecular Diagnostics Unit of the Cork Institute of Technology, Cork, Ireland, for investigation. These strains were characterized by several methods, including polyacrylamide gel electropherotyping and G and P genotyping. A subset of the G types was confirmed by nucleic acid sequencing. The most prevalent types found in this collection included G1P[8] (n = 106; 32.1%), G2P[4] (n = 94; 28.5%), and G4P[8] (n = 37; 11.2%). Novel strains were also detected, including G1P[4] (n = 19; 5.8%), and G4P[4] (n = 2; 0.6%). Interestingly, mixed infections accounted for 18.8% (n = 62) of the total collection, with only 3% (n = 10) which were not G and/or P typeable. Significantly, six G8 and five G9 strains were identified as part of mixed infections. These strains have not previously been identified in Irish children, suggesting a greater diversity in rotavirus strains currently circulating in Ireland.