Nucleotide and amino acid analyzes of the VP4 gene of human rotaviruses isolated both in Paraguay and worldwide were carried out in order to increase our knowledge about the complex pattern of evolution of this virus in nature. Paraguayan strains bearing the P[8] genotype were grouped in the lineages P[8]-1, P[8]-2, and P[8]-3. Regardless of the year of detection, all of the G4 and G9 strains were related to lineage P[8]-3, whereas the G1 strains were related to the three lineages detected in Paraguay; this fact reinforces the notion of the existence of constraints within specific populations of rotavirus strains except for the G1 strains. In addition, we propose a phylogenetic classification for the P[4] strains in five different lineages (i.e. P[4]-1 to P[4]-5). The findings presented in this paper reinforce the importance of a continuous surveillance of rotavirus strains in order to predict the possible variants that will circulate in a country, and ultimately improve current vaccination programs.