Objective: Foreign Body aspiration (FBA) is a common cause of respiratory distress in children between 6 months and 3 years old. Early diagnosis and management will decrease complications and mortality. Material & Methods: A retrospective study was done on records of 140 patients with FBA between 1998-2003 at Imam Reza hospital a tertiary university hospital of Mashhad University of Medical Sciences. Findings: From 140 patients, 62% were male and 82.2% were under 6 years old. History of chocking was the most frequent clinical finding (77%), other clinical findings were wheezing (38.6%), decreased breathing sounds (42.1%), cough (20%), respiratory distress (15.4%), fever (15.4%) and stridor (6.6%). Chest radiography was normal in 42.1%. The time of diagnosis was the first day in 42.3%. The most common aspirated Foreign bodies were seeds (40.7%) and the most common site of FBA was right bronchus. Complications consisted of 27.9 % pneumonia, 17.1% persistent and resistant pneumonia, cardio–respiratory arrest in 2 % and lung abscess in 0.7%. Mean hospital stay was 2 days and mortality rate 2.9%.Conclusion: Foreign Body aspiration can occur at any age especially in children under 6 years in the absence of predisposing factors. Normal auscultation and chest X-ray do not rule out the diagnosis of FBA; high suspicion is the important clue for diagnosis.