The ability of adult Brown Leghorn cockerels to regulate food intake precisely was tested by measuring their responses to dietary dilutions with 100, 200, 300 and 400 g kaolin per kg diet. When changed from their original undiluted mash diet, cockerels continued gaining body weight with 100 and 200 g kaolin/kg dilutions, maintained weight with 300 g/kg and lost weight continuously with 400 g/kg. With all dilutions, the birds eventually adjusted weights of dry matter digested per day to the same levels as with the original basal diet. This took a few days with 100 g kaolin/kg, a week or more with 200 and 300 g/kg, and about three weeks with 400 g/kg. They achieved this mainly by increasing consumption of diluted food to maintain their original intake of basal diet. With 400 g kaolin/kg they were unable to compensate fully in amount eaten, but digestibility of the basal diet increased significantly. It is suggested that, given the right conditions, fowls may be able to compensate accurately when challenged with a range of dietary dilutions, the upper limit depending on the density of filler used.