[en] A 3 week old Friesian foal colt was presented with a history of respiratory distress since birth. Endoscopy showed obstruction of the right nasal passage to the nasopharynx. Computed tomography (CT) was performed to further characterize this unilateral blockage: images showed demonstrated a complete membranous obstruction of the ventral meatus, together with a deviation of the vomer bone to the left. The diagnosis of unilateral choanal atresia was confirmed. This is the first report describing CT features of choanal atresia in a foal.