In a selected group of 103 babies referred with neonatal conjunctivitis Neisseria gonorrhoeae was isolated from 11 and Chlamydia trachomatis from 33. Concurrent infection was present in three. On toddler sibling developed chlamydial conjunctivitis. After treatment C. trachomatis was re-isolated from six babies during the follow-up period. The discharge started one to three days after delivery in only three babies with gonococcal conjunctivitis and at five to eight days in eight babies. One baby was delivered by caesarean section. N. gonorrhoeae was isolated from four asymptomatic fathers, all of whom had urethritis. The mean onset of discharge in the 33 babies from whom Chlamydia was isolated was 7-1 days. One baby was delivered by caesarean section. Chlamydial conjunctivitis was associated with a high incidence of prematurity and of postpartum infection in the mother. Ten fathers of Chlamydia-positive babies were examined. C. tachomatis was isolated from four, all of whom were asymptomatic but had low-grade urethritis. These findings confirm the pathogenic role of C. trachomatis in the cervix and indicate the importance to the family of an adequate microbiological investigation of neonatal conjunctivitis.