The clinician is often held responsible for obstetric events that are suspected of being related to cerebral palsy. To review the incidence of cerebral palsy and to aid the clinician in this situation, a search of published studies was conducted. Composite rates of cerebral palsy in different birth weight infants and cerebral palsy with and without serious mental retardation were calculated. The cumulative incidence rate at the age of 5 to 7 years was 2.7 cases of cerebral palsy for 1000 birth cohorts. Approximately 36% of all cerebral palsy occurred in the infant less than 2500 gm. Serious mental retardation (intelligence quotient less than 50) accompanied cerebral palsy approximately 30% of the time for the term infant and 18% of the time when the infant was less than 2500 gm. On the basis of a past estimation that 70% of cerebral palsy is of antepartum or unknown origin, the term infant at risk for intrapartum-attributed cerebral palsy may be about 1 in 2000 term births.