Primary ciliary dyskinesia (PCD) results in chronic nasal symptoms and chest disease leading to bronchiectasis. We noted a number of patients referred for diagnostic testing whose initial results suggested PCD due to an inner dynein arm or radial spoke defect but in whom no abnormality was found on retesting. The present study was an audit of all patients referred for PCD diagnostic testing over a 3-yr period whose initial electron microscopy (EM) and beat pattern analysis suggested an inner dynein arm or radial spoke defect. 21 patients referred for diagnostic testing for PCD suspected of an inner dynein arm defect and six suspected of a radial spoke defect on initial EM and beat pattern analysis had repeat testing performed. On repeat testing, five patients initially suspected of an inner dynein arm defect and one with a radial spoke defect had normal EM and beat pattern, leading to the initial diagnosis being questioned. Patients suspected of PCD due to an inner dynein arm defect or radial spoke defect should have the diagnosis reassessed if it has been based on only one diagnostic sample.