The settlement site of Sion-Avenue Ritz, located in central Valais (Switzerland), was occupied during the middle Neolithic (Cortaillod). The analyzed faunal remains come mainly from dump pits and they are mostly consumption or butchery wastes, belonging to domestic animals. One exceptional pit contained the skeletons of at least 15 sheep in partial anatomical connection. The zooarchaeological analysis of these special remains show that the animals, ranging from very young to sub-adult individuals, were very likely to have been thrown complete in the pit, simultaneously and probably following the bodies cremation. Although several hypothetical interpretations of this context are essayed, one is considered the most tenable by the author: the stock may have died from an epizootic which hit the flock during spring, and were buried in a pit specially dug for them after they were partially burnt. The zooarchaeological analysis of this site, particularly of the 15 sheep pit, yields data of an exceptional quality in the context of Neolithic settlements in the middle and high Rhone valley where faunal remains are usually poorly preserved. It allows, among other things. An attempt to extrapolate interpretations on the stocks assessment and to understand the breeding conditions of these animals.