An ultrastructural analysis of the connections of the amygdala with the parabrachial nuclei (PBN) was carried out after electrolytic lesions or injections of horseradish peroxidase in the amygdala. Degenerating and labeled terminals originating from the amygdala formed axosomatic and axodendritic synapses in the PBN. In some instances, anterogradely labeled terminals synapsed with retrogradely labeled neurons. These results demonstrate that the amygdala and PBN have close reciprocal synaptic connections.