1. Characteristics of structure in the sympathetic neuron of amphibia were reported. A neuron and its satellite cell in the sympathetic ganglion of frog and toad form a peculiar shape which resembles to the octopus.2. Two types of synaptic vesicles were differentiated. One has a peak at 500A in size distribution curve, and the other at 1, 000A. The vesicles of the latter have dense cores.3. Adrenergic transmission mechanism in the sympathetic ganglion was suggested, at least in some of the neurons in it.