The results of a collaborative study of bilateral spastic cerebral palsy (BSCP) between south-west Germany and western Sweden are reported, comprising 249 children in south-west Germany and 264 children in western Sweden. A severe gross motor disability was present in 65 per cent of the German and 62 per cent of the Swedish children; learning difficulties or mental retardation in 73 and 76 per cent; active epilepsy in 28 and 26 per cent; and severe visual disability in 20 and 19 per cent, respectively. Severe disabilities were especially pronounced in children with normal birthweights, in whom the most severe subtypes of BSCP were also found. Leg-dominated BSCP was the predominant subtype among low-birthweight children, but also occurred in more than half of the normal-birthweight children. The authors conclude that the two series were comparable, and that reliable results between countries can be obtained if clear-cut classifications and definitions are used.