<h2>Summary</h2> Primary ciliary dyskinesia is a genetically and clinically heterogeneous syndrome. Impaired function of motile cilia causes failure of mucociliary clearance. Patients typically present with neonatal respiratory distress of unknown cause and then continue to have a daily wet cough, recurrent chest infections, perennial rhinosinusitis, otitis media with effusion, and bronchiectasis. Approximately 50% of patients have situs inversus, and infertility is common. While understanding of the underlying genetics and disease mechanisms have substantially advanced in recent years, there remains a paucity of evidence for treatment. Next-generation sequencing has increased gene discovery, and mutations in more than 40 genes have been reported to cause primary ciliary dyskinesia, with many other genes likely to be discovered. Increased knowledge of cilia genes is challenging perceptions of the clinical phenotype, as some genes reported in the last 5 years are associated with mild respiratory disease. Developments in genomics and molecular medicine are rapidly improving diagnosis, and a genetic cause can be identified in approximately 70% of patients known to have primary ciliary dyskinesia. Groups are now investigating novel and personalised treatments, although gene therapies are unlikely to be available in the near future.