Two hundred and thirty four patients (adults and babies) with conjunctivitis were investigated by taking eye swabs and in addition by taking per-nasal swabs. Chlamydia trachomatis was isolated from 20 patients and adenovirus from 14 patients. Per-nasal swabbing led to a 53% increase in chlamydia diagnosis and a 27% increase in the diagnosis of adenovirus infection. It is suggested that per-nasal swabbing has an important role to play in detecting chlamydial conjunctivitis which itself may be an indicator for high morbidity in patients and their contacts.