Anticipating imminent introduction of a vaccine against Rotavirus A (RVA) in Vietnam, baseline information on the whole genome of representative strains is needed to understand changes in circulating strains that may occur after vaccine introduction. In this study, we sequenced the whole genome of two G2P[4] strains detected in Nha Trang, Vietnam in 2008, the last period when virtually no rotavirus vaccine was used in the country. The two strains were >99.9% identical in sequence and had a typical DS-1 like G2-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2 genotype constellation. Analysis of Vietnamese strains with >184 G2P[4] strains retrieved from GenBank placed Vietnamese strains in one of the lineages commonly found among contemporary strains except the NSP2 and NSP4 genes. The NSP2 genes belonged to a previously undescribed lineage that diverged from Chinese sheep and goat RVA strains including a Chinese rotavirus vaccine strain LLR with a 95% nucleotide identity, and the time of the most recent common ancestor was 1975. The NSP4 genes belonged to an emergent lineage (VIII) together with Thai and US strains, adding further diversity to ever diversifying NSP4 lineages. Thus, there is a need to enhance surveillance on locally-circulating strains from both children and animals at the whole genome level in addressing the effect of rotavirus vaccines on changing strain distribution.