More than 32,000 children in a prenatally-defined cohort were examined four months after birth, and were re-examined at the age of seven years to determine the presence of cerebral palsy. Observations from the examination at four months were investigated as predictors of cerebral palsy, and the most reliable individual sign was increased muscle tone in neck, arms, legs or trunk. On completion of the physical examination at four months, the neurological status of each infant was assessed. Of the children considered to be normal, one in 1000 had cerebral palsy by the age of seven years, compared with one in 100 of those thought to be suspect. Of the children who had been definitely neurologically abnormal at four months, one in seven had disabling cerebral palsy by early school-age. The predictive power of abnormal physical findings increased with the number of abnormal findings with failure to meet motor milestones. Four-month-old infants who passed all milestone measures had a very low rate of later cerebral palsy, even if they had had abnormal physical findings. Examination of four-month-old infants permits the clinician to recognize children at widely different levels of risk of chronic motor handicap.