Cerebral palsy comprises an important component of paediatric and obstetric practice and has major medico-legal implications. The prognosis for survival in cerebral palsy determines the financial provision made in cases that come to litigation. Issues of data quality and estimation methods are critical. Estimating the probability of survival in cerebral palsy based on clinical experience is liable to serious error unless numerical data can be produced. Only an actuarial analysis based on a standard life table of cases of cerebral palsy will enable a valid estimate of survival. Construction of the table requires a total cohort of cases of cerebral palsy with their date of birth. Each case must conform to a specified definition of the syndrome. Notification of all those who die, with their date of death is mandatory. Estimating the probability of survival according to the severity of functional disability requires specific definitional criteria for each severity category and for those categories to be mutually exclusive. Survival is significantly poorer in those with severe disability. Severe cognitive, motor (manual and ambulatory), and visual disabilities have independent effects on the probability of survival. Severe hearing disability does not add additional information when the other four functional disability categories are included.