Of 99 infants treated for hyaline membrane disease (HMD) by artificial ventilation during the period of 1967 to 1970 in the neonatal ICU: six died during the follow-up period, four of whom had severe neurological damage; 13 were lost to follow-up examinations; 80 were followed for two to five years.Of the 80 who were followed; 39 (48%) developed normally, 29 (36%) had problems of moderate severity with acceptable handicaps; 12 (15%) had severe neurological damage.There was a good correlation between neonatal neurological status and subsequent clinical outcome. The correlation between the neonatal EEG and clinical outcome was also good. Babies with severe neurological abnormalities during the neonatal period were found to have a high incidence of late sequelae.