Twelve human cervical-thoracic sympathetic ganglia have been studied 3 h after a sudden death. Peculiar osmophilic bodies in the neuronal mitochondria have been revealed electron microscopically. In the preparation successive stages of these bodies formation are seen. Ultrastructure of afferent neural terminals adjoining the sympathetic neuron bodies but divided from them with a gap space is described. The structure of the receptors in the ganglia and that of the sympathetic contacts are compared, the latter are predominantly axodendritic.