The speech perception and speech production performance following cochlear implantation of congenitally deaf children and children deafened by meningitis were analysed. Three groups consisting of 70 congenitally deaf children, 22 children deafened by meningitis before two years of age and 14 children deafened by meningitis after two years of age were compared. The group deafened by meningitis after two years of age demonstrated significantly better speech perception than the other two groups. Their speech production appeared better but did not achieve statistical significance compared with the other two groups. There was no significant difference in either speech perception or speech production between the congenitally deaf group and the group deafened by meningitis before two years of age.