The inhibition of pancreatic lipase activity by extracts of raw, milled or processed cereals was measured in vitro. The inhibitory activity was high in durum wheat, soft wheat and millet, moderate in barley and white sorghum and very low in red sorghum. Milling whole-grain into flours markedly decreased the lipase inhibitory activity in all species. In durum wheat, the germ and the aleurone-layer fraction exhibited the highest inhibitory activity. Processing of soft wheat by bread making, popping, flaking, drum-drying and extrusion-cooking, or durum wheat by making pasta markedly decreased the lipase inhibitory capacity. Extractible proteins were implicated in the inhibition process. These effects also had some nutritional implications.