The course of the right recurrent laryngeal nerve (RLN) within the vagus nerve was examined under the light microscope, using horseradish peroxidase. In the higher cervical vagus, i.e. from the base of the skull to the level of the carotid bifurcation, the recurrent laryngeal nerve fibres formed on average 5-6 small separate bundles (15–40 µm in diameter); in the middle cervical vagus, on average from the level of 8-14 mm caudally from the bifurcation, there were fewer bundles with a diameter range of 10-50 µm; in the lower cervical vagus, indicated as being from 14-26 mm caudally from the middle cervical vagus, the bundles merged into a single larger bundle (50–7