A total of 200 clones of reassortants were generated in vitro between simian rotavirus SA11 (SA11-L2 strain) and each of five human rotavirus (HRV) strains with different antigenic specificities and RNA patterns. When culture fluid coinfected with parent viruses was subjected to repeated selection with anti-HRV-VP4 and anti-SA11-VP7 neutralizing monoclonal antibodies, all yielded progenies were antigenic mosaic reassortants possessing VP4 and VP7 derived from SA11 and HRV, respectively. In genomic analysis of viral RNA by PAGE, two and five different genotypes were identified in 40 clones, generated between SA11 and HRV strain Hochi (G serotype 4, G4) and between SA11 and KU (G1), respectively. In contrast, 11 and 17 genotypes were found in progenies between SA11 and subgroup I G2 HRV strain HN126 or DS-1, respectively. Although SA11 genes, except for the VP7 gene, were predominant in most reassortants, gene 5 was preferentially selected from HRV. Incorporation of HRV segments 1, 3 and 10 into progenies was more frequent in SA11 x HN126 and SA11 x DS-1 reassortants than in other reassortants. These results indicated that the extent of diversity of reassortant genotypes differs between the two groups of the parental HRV strain; one has subgroup I specificity and a short RNA pattern (DS-1 genogroup), while the other has subgroup II specificity and a long RNA pattern (Wa genogroup).