Objective To examine the synaptic structure and glutamatergic transmitter of the pathway linking the anterior thalamic nucleus(ATN) and the subicular complex. Methods The HRP tracing and post embedding immunogold technique were used. Results In the anterior thalamic nucleus, anterograde HRP labelled terminals contained clear round synaptic vesicles and several mitochondria, and formed asymmetric synaptic contacts with HRPlabelled or nonHRP labelled dendrites. The highest densities of immunogold particles following glutamate immunostaining were found in HRPlabelled terminals and similar axon terminals devoid of HRP reaction product, They formed asymmetric synaptic contacts(Gray type Ⅰ) with dendrites. The average density of those immunogold particles was more than 3 times higher than that of the gold particles in the dendrites of their contacts and over 6 times higher than that of the particles in the terminals that formed symmetric synapses (Gray type Ⅱ). In two serial GABA immunogold reactive sections, Gray tpye Ⅱ terminals were heavily labeled whereas Gray type Ⅰterminals displayed a very slight labelling. In glutamate immunogold reactive sections, Gray type Ⅱ terminals were slightly labeled. A GABA positive terminal which formed symmetric synapses with HRP-labeled dendrites and the terminal which formed asymmetric synapses converged on the same dendrite. Conclusion The terminals of projection neurons in the pathway linking the anterior thalamic nucleus and the subicular complex are glutamatergic. In anterior thalamic nucleus corticothalamic projection neuron term