Grasses form the most important source of airborne pollen in the United Kingdom. This article reviews the ecological, geographical and historical features of grassland utilization relevant to pollen production. During the past half century extensive agricultural management, with botanically diverse swards and late (post anthesis) mowing for hay, has been progressively replaced by more intensive management with more reliance onLolium perenneand early mowing for silage. The role ofDactylis glomerataandPhleum pratensehas declined. A decrease in the June pollen catch supports the hypothesis that these changes have affected the quantities of pollen released. Incidence of hay fever shows geographical variation with climate, topography and vegetation type. Recent policy changes intended to decrease agricultural production and to meet environmental objectives may, in future, further affect the types and quantities of pollen produced.