Food intake is one of the most important factors governing animal performance. Amongst the dietary variables that affect food intake, both deficiencies and excesses of protein and amino acids are known to be important. Moreover, excesses of certain amino acids may alter protein utilisation and consequently animal performance. Although large amino acid excesses have been shown in various experiments to alter food intake of weanling or growing pigs (Baker, 1993) the effects of the moderate amino acid excesses that may arise in normal diet formulation have been little studied. The objective of this experiment was to study if a 100% excess of single amino acids in a diet with an 'ideally' balanced amino acid pattern could alter daily food intake, average daily gain or food conversion ratio in growing pigs. The excesses used were relatively small to investigate the effect of excess within the range that might be found in practice.