Describing the epidemiology of cerebral palsy (CP), its impairments and risk factors. Literature review 1965-2004. Search terms: Cerebral palsy, incidence, prevalence, impairments, risk factors. In the last 40 years the prevalence of CP has risen to well above 2.0 per 1000 life births. In this time span the proportion of low-birthweight infants rose, the proportion of diplegia decreased, while the proportion of hemiplegia increased. CP is more prevalent in more deprived socio-economic populations. The majority of people with CP have the spastic syndrome of which the diplegic group is the smallest. Dependent on the subgroup of CP, 25-80% have additional impairments. A large proportion has some kind of cognitive impairment; the prevalence varies with the type of CP and especially increases when epilepsy is present. Epilepsy is present in 20-40%; it is most common among the hemi- and tetraplegics. Sensibility of the hands is impaired in about half. Chronic pain is reported by more than a quarter of the adults. Up to 80% have at least some impairment of speech. Low visual acuity is reported in almost three-quarters of all children. Half of all children have gastrointestinal and feeding problems. Stunted growth occurs in a quarter, while under- or overweight problems are present in half of the children. Almost 70% of people with spastic CP have abnormal brain CT findings; abnormal cranial ultrasounds is most strongly associated with hemiplegia, normal cranial ultrasounds with diplegia. The most important risk factors for CP are low birthweight, intrauterine infections and multiple gestation.