For many years the notion that brain damage causes less impairment in children than in adults (sometimes known as the 'Kennard Principle') has enjoyed widespread support among scientists and clinicians. More recently neuroscientists have questioned the Principle, most now taking an opposing view that damage to the rapidly developing brain can be more harmful than equivalent damage in adulthood. Many clinicians, however, appear reluctant to reject the Kennard Principle. This study investigates the extent to which the Kennard Principle still guides the judgement of different groups of health-care professionals (neurosurgeons, neurologists, neuropsychologists, general practitioners, nurses, physiotherapists, occupational therapists, and speech therapists). Subjects were asked to estimate the extent of recovery in clinically based but fictitious case studies which differed only in the reported age of the patient. The professions differed in their levels of optimism regarding the extent of recovery to be expected, but all predicted better recovery in younger patients (under 10) than in adults with otherwise similar brain injuries. The results are discussed in terms of their implications for the treatment of brain injuries in the young.