Pneumonia is a common cause of morbidity and mortality in children less than five years of age. One of the complications and a significant predictor of death from pneumonia is hypoxaemia. Prompt administration of oxygen reverses hypoxaemia and its effects. Knowledge of the prevalence of hypoxaemia and clinical signs associated with it may guide use of oxygen in the management of childhood pneumonia in Federal Medical Centre, Owerri. This study was carried out to determine the prevalence of hypoxaemia in children with pneumonia and its relationship with age, duration of illness and clinical signs.