The effect of different grazing systems on the botanical composition of North Island hill sheep pastures was examined in three experiments over a period of four to eight years. In two experiments on steep, developed hill country the effects of mob-stocking did not differ markedly from those of set-stocking. In the third experiment, unimproved and improved pastures were maintained at two heights by hard and lax set-stocking. In Improved pastures, perennial ryegrass (Lolium perenne) increased under hard grazing and Yorkshire fog (Holcus lanatus) increased under lax grazing. In unimproved pastures weeds increased under hard grazing.