Although it is recognized that an enlarged thyroid may occasionally cause tracheal compression, the incidence in euthyroid goiter is unknown. Twenty patients with nontoxic goiter were investigated for upper airway obstruction. Although none of them had dyspnea as a chief complaint, on direct questioning 9/20 had a history of shortness of breath on exertion and choking sensation. Upper airway obstruction was detected in 7/20 (35%) by roentgenography, 12/20 (60%) by flow volume loop (FVL), and in 16/20 (80%) by combined roentgenography and FVL. After therapy for goiter, there was a reduction in the size of the goiter and an improvement in FVL in the whole group. The statistically significant change occurred in peak expiratory flow (P less than .01) and peak inspiratory flow (P less than .05). These findings and the change in configuration of the curve suggested less upper airway compression. We conclude that goiter often causes unsuspected upper airway obstruction, usually slow in onset and not noticed by the patient.