One of the potential advantages of choice feeding is that it could remove the need to formulate and manufacture complete diets for pigs. The simplest and most attractive option would be where pigs could select an adequate diet from basic raw feed ingredients offered separately. However, intrinsic differences in the composition of feed ingredients, particularly naturally occurring antinutritional and toxic factors, may influence selection, nutrient intake and performance. The aim of this study was to determine whether growing pigs could select an adequate diet when offered an unrestricted choice between a cereal and a protein supplement.