ABSTRACTThe measurement of primary production and utilization of heather moors is a necessary part of studies aimed at understanding and ultimately improving secondary (animal) production.Heather is a woody perennial and presente many problems peculiar to itself. With management in mind a more precise method of classification and description of heather moors is suggested.The measurement of quantity of production in terms of standing crop, total edihie DM and annual DM production are described in detail. Chlorophyll extraction techniques are descrihed, these heing more rapid than hand separation and enabling many more samples to be handled.Digestibility and voluntary intake of heather as indices of quality are briefly discussed.A method for the calculation of grazing pressure or utilization is described. The method measures the percentage of available edible (photosynthetic) material which is consumed.