International audience ; We have amplified, cloned and sequenced (part of) the open reading frame of the S1 segment encoding the $sigma$ C protein of avian reoviruses isolated from chickens with different disease conditions in Germany and The Netherlands during 1980 up to 2000. These avian reoviruses were analysed phylogenetically and compared with sequences of avian reoviruses in the Genbank database. The avian reoviruses could be grouped in 5 different genotyping clusters and this classification was identical when the sequences were compared of the 5$'$ end, the 3$'$ end or the whole open reading frame of the $sigma$ C protein. Therefore sequencing of either part of the gene encoding the $sigma$ C protein seems to be reliable for classification. We were unable to identify a correlation between $sigma$ C sequences of the avian reoviruses and the disease condition they were isolated from. The sequences found in The Netherlands and in Germany are, like those in Taiwan, more dispersed than the known avian reovirus $sigma$ C sequences in the USA and Australia. We did not establish temporal or geographic differences in the avian reoviruses studied.