First, we longitudinally analyzed 177 cerebral-palsied children (CP) who were born in Kyoto City between 1977 and 1985. They were all visited St. Joseph Hospital for Crippled Children in Kyoto during the period 1977 to 1991 in order to investigate the relationship between the prognosis of perinatal care and the changing panorama of CP in Kyoto. The average occurrence rate of CP per 1,000 live birth during the 9 years in Kyoto was 1.12. 177 CP were divided into 3 groups according to their birth years: 1977-1979 (47 CP); 1980-1982 (62 CP); and 1983-1985 (68 CP). Then we compared the distribution of birthweights and gestational periods among the 3 groups. We found a significant increasing trend in the percentage of CP in babies with birthweight less than 2,000 g. Second, we examined 162 CP; 15 born outside of Kyoto were excluded because of extraneous influences of perinatal care. 162 were divided into 3 groups according to their birth years: 1977-1979 (44); 1980-1982 (56); and 1983-1985 (62). We also compared the risk factors and prognosis according to the birthweights and gestational ages among the 3 groups. This study revealed a decreasing trend in the frequency of convulsions of full term CP, dyspnea and oxygen administration of premature CP in the neonatal period. At the same time, the motor development of CP without mental retardation had improved significantly in the later period. However, in the last 3 years the distribution of the severity of motor disturbance at 4 years of age among CP with birthweight of 1,000-2,000 g was either mild or severe.(ABSTRACT TRUNCATED AT 250 WORDS)