Analysis of the genomic dsRNA of rotaviruses isolated from calves with subclinical infections has revealed eight calves excreting group A viruses with unusual genome profiles. Two of these virus strains, C7-176 and C7-183, were grown and cloned by plaque purification in cell culture. Examination of their genome profiles after cloning showed that the unusual pattern had been retained. They were without RNA segment 11 but had an extra band (6a) migrating between segments 6 and 7. However, they contained the triplet of segments 7, 8 and 9, of similar size, which is characteristic of group A rotaviruses. The number and mol. wt. of the intracellular polypeptides induced by these viruses were similar to those of the bovine group A rotavirus UK strain. Analysis of the RNA transcripts produced by the transcription in vitro of purified C7-183 virus showed that segment 6a produced a large RNA transcript of corresponding size. After isolation, this transcript was translated in a rabbit reticulocyte lysate preparation and yielded a single polypeptide, vp11, equivalent to the product of segment 11 of rotaviruses with typical genome profiles.