The production of 5 grasslands in the northern Pennines at altitudes ranging from 480 m to 840 m was measured by a cage technique. Cages were moved to fresh positions monthly, and caged and grazed plots were cut by hand-shears. The herbage was sorted into its principle components, and their monthly growth calculated. This allowed losses caused by the death of tissues after summer frosts and the incorporation of dead material into the soil to be ne?glected in the calculation of adjusted totals of annual growth. Two lowlevel grasslands, Knock Ore Gil at 480 m and Tees at 518 m, gave adjusted growth totals of 1788 and 1947 kg/ha (dry weight) respectively. Both were Agrosto-Festuceta, but a similar sward, Knock Fell at 747 m, gave only 759 kg/ha in 1962 and 886 kg/ha in 1963. Production values were also low at Hard Hill (678 m) and Little Dun Fell (822-840 m), being 915 kg/ha and 559 kh/ha respectively. Both were Festuceta on sand-stone-derived soils. These production totals are from 10 to 40% less than those at the same sites obtained by harvesting swards ungrazed throughout the growing season.