Different protocols of food deprivation were used to bring two groups of juvenile threeβspined sticklebacks Gasterosteus aculeatus to the same reduced body mass in comparison with a control group fed daily ad libitum. One group experienced 1 week of deprivation then 2 weeks on maintenance rations. The second group experienced 1 week of ad libitum feeding followed by 2 weeks of deprivation. The deprived groups were reduced to a mean mass of c. 80% of controls. The compensatory growth response shown when ad libitum feeding was resumed was independent of the trajectory by which the threeβspined sticklebacks had reached the reduced body mass. The compensatory response was sufficient to return the deprived groups to the mass and length trajectories shown by the control group within 4 weeks. There was full compensation for dry mass and total lipid, but incomplete compensation for lipidβfree dry mass. Hyperphagia and increased growth efficiency were present in the reβfeeding phase, but there was a lag of a week before the hyperphagia was established. The consistency of the compensatory response of immature threeβspined sticklebacks provides a potential model system for the analysis and prediction of appetite and growth in teleosts.