On many western rangelands, cattle and elk use the same forages but during different seasons. This can place these species into indirect competition or amensalism. The objective of this study was to examine the effects of summer grazing by cattle upon the winter forage quality for elk. Individual plants of bluebunch wheat glass (Agropyron spicatum), rough fescue (Festuca scabrella), and ldaho fescue (Festuca idahoensis) were monitored for phenological stage when summer grazed by cattle on a Rocky Mountain elk (Cervus elaphus nelsoni) wintering range in the Elkhorn Mountains, Montana.  Assessment of winter chemical composition of these three key forage species indicated no deleterious effects of summer grazing by cattle stocked at 3.7 ha/AUM upon the winter forage quality. In general, rough fescue and ldaho fescue had lower average fiber fractions and higher crude protein than bluebunch wheatgrass. Under deferred rotation cattle management, the primary winter elk forage management concern appears to be forage quantity rather than quality.