Objectives: To determine the efficacy of our nasal brush biopsy technique to diagnose primary ciliary dyskinesia. Study Design: Retrospective chart review at an urban children's hospital Methods: We obtained medical records of all patients who underwent an endoscopic guided ciliary brush biopsy from January 2000 to June 2008. Data recorded included the procedure date, biopsy location, presence of motility on light microscopy, and whether specimen was sent for electron microscopy and those results. Results: Sixty pediatric patients between the ages of 16 months and 17.3 years with chronic sinusitis (35 males, 25 females) were identified. Three were excluded because biopsies were taken from a non nasal location. Forty-seven specimens had light microscopy evaluation only, as normal motile cilia were identified. Ten had haphazard or absent motility and required further evaluation with electron microscopy. Electron microscopy ruled out defects for three samples, was non-diagnostic for five, and the remaining two reports could not be found. Overall, in 47/57 (82%) cases, light microscopy alone ruled out primary ciliary dyskinesia (PCD). Using both methods, there was a 91% success rate in ruling out PCD. Conclusions: Obtaining an endoscopic biopsy with a cytosoft cytology brush (Camarillo California) from the posterior portion of the inferior turbinate gave sufficient specimen to examine for PCD. Light microscopy alone or in concert with evaluation by electron microscopy confirmed normal cilia in 91% of specimens ruling out the diagnosis of PCD. The algorithm suggested is simple and has high success in allowing the clinician to exclude the diagnosis of PCD in the patient with chronic or recurrent upper respiratory infections.