This session will provide the learner with an evidence based approach to diagnosing primary ciliary dyskinesia (PCD). The reference standard diagnostic test for PCD for the past 50 plus years has been ciliary ultrastructural abnormalities detected with a transmission electron microscope. We now know that this reference standard is flawed with significant false positive and false negative results. This workshop will educate attendees about a recently completed ATS guidelines project on the diagnosis of PCD, which evaluates evidence from the explosion of genetic and molecular scientific discovery on ciliopathies that has taken place in the past decade. Topics covered will include the utility of genetics, videomicroscopy, and nasal nitric oxide testing for the diagnosis of PCD.