This case study reports on two infants, 5 and 6 months of age, respectively, with chronic interstitial lung disease who presented with failure to thrive, tachypnoea, rales and mild hypoxaemia. Epstein-Barr virus (EBV) was detected by in situ hybridization in lung biopsy specimens and by EBV-deoxyribonucleic acid-polymerase chain reaction (PCR) in bronchoalveolar lavage (BAL) fluid in one patient and by in situ hybridization and PCR analysis in BAL fluid in the second patient. There was serological evidence of immunoglobulin G antibodies to EBV capsid antigen by indirect immunofluorescence in both patients. After 7 months of respiratory symptoms one patient was successfully treated with a 10 day course of intravenous ganciclovir followed by oral acyclovir for 20 days. The other patient became symptom free after 3.5 months of respiratory symptoms, without any specific antiviral medication. During a follow-up of 2 and 1.5 yrs, respectively, both infants remained symptom free and showed normal physical development.