The sequences of the gene encoding VP7 (the major outer capsid protein) from one bovine and three human rotavirus strains were determined because of their unusual VP7 specificities. Two of the human strains (PA 169 and PA 151) had VP7 serotype 6 specificity whereas the two other strains, recovered from a child (HAL 1166) and a calf (678) belonged to VP7 serotype 8. The serotype 8 strains exhibited a high degree of sequence conservation when compared with each other and with other serotype 8 strains previously sequenced. The serotype 6 human strains shared a greater degree of sequence similarity with previously reported serotype 6 bovine strains than with other rotavirus serotypes; however the degree of sequence similarity among PA 169, PA 151 and the bovine strains was lower than had been previously reported for strains belonging to the same serotype. The demonstration of rotavirus serotypes that are shared between human and animal species supports the concept that interspecies transmission occurs and may play a role in rotavirus evolution.