A 2-year surveillance was performed in Kathmandu, Nepal, by collection of stool specimens from 1139 children aged <5 years who were hospitalized for acute diarrhea from November 2005 through October 2007. Of the 1139 samples, 379 (33%) had rotavirus strains identified by enzyme-linked immunosorbent assay; the most prevalent G type was G12, accounting for 50% of typed strains in 2005-2006 and 29% in 2006-2007, followed by G1 (26%) in 2005-2006 and by G9 (28%) and G2 (20%) in 2006-2007. The most prevalent P type was P[8], accounting for 47% of strains in 2005-2006 and 35% in 2006-2007, followed by P[6] (37% in 2005-2006 and 33% in 2006-2007) and P[4] (10% in 2005-2006 and 24% in 2006-2007). Of combined genotypes, G12P[6] was the most prevalent, accounting for 34% of strains in 2005-2006 and 24% in 2006-2007, followed by G1P[8] (23%) in 2005-2006 and G2P[4] (20%) in 2006-2007. An unusually high detection of G12 strains underscores the importance of continued surveillance of rotavirus strains.