Respiratory syncytial virus (RSV) is an important cause of lower respiratory tract infection (LRTI) in infants and children. There is growing evidence of severe RSV disease in infants with neuromuscular diseases and immune deficiency syndromes. Factors predisposing to a more severe course of RSV disease in neuromuscular diseases include the impaired ability to clear secretions from the airways due to ineffective cough, respiratory muscle weakness, high prevalence of gastro-oesophageal reflux and swallowing dysfunction which leads to aspiration. Similarly, pulmonary disease is a common presenting feature and complication of T-cell immunodeficiency. Infants with severe congenital and acquired immune deficiency syndromes may demonstrate prolonged viral shedding in RSV LRTI and are reported to have increased morbidity and mortality associated with RSV infection. Although not indicated in most guideline statements, palivizumab prophylaxis for these uncommon underlying conditions is under consideration by clinicians. Prospective studies are needed to determine the burden of RSV disease in these children.