The cytoarchitecture of the superior cervical ganglion of the common tree shrew was investigated by scanning electron microscopy using the vascular cast technique in conjunction with digestion by collagenase-hyaluronidase/HCl. The main cellular constituents were found to be multipolar neurons that were densely distributed throughout the ganglion. These neurons were covered with a smooth cytoplasmic sheath of satellite cells. After the removal of this sheath by digestion of increased duration, the blebs or knobs on the neuronal surfaces became evident. A meshwork of nerve fibers over the surface of neurons was also observed. Preganglionic sympathetic nerve fibers, giving rise to fine branches that ran toward the postganglionic sympathetic neurons before forming synapses, were demonstrated. Groups of neurons surrounded by capillary loops were also frequently observed.