With the increased utilisation of land throughout the West of Scotland by the Forestry Commission, the problems arising from the integration of forestry and sheep-farming demand special attention. The Hill Farming Research Station at Lephinmore in Argyll has provided an opportunity over the past four years for the initiation of long-term experiments. These involve various preparatory studies and this paper describes a preliminary survey of the fragments of herbage in the rumen of sheep (after slaughter) with the object of assessing the seasonal variation in their grazing selectivity for heather. The Lephinmore hill is predominantly of heather. Since there are many divergent views as to the preference of sheep for heather, this survey was designed in a rather novel, indirect way to obtain more precise information. The rôle of heather as a dietary constituent is of added significance because, after the afforestation of the lower slopes of a hill, the sheep are then restricted to higher ground where there is greater snow cover in the winter.