The origin of the afferents of the thalamic anterior paraventricular and parataenial nuclei (PVA-PT) in the rat was studied with fluorescent retrograde tracing method. After iontophoretic application of Fluoro-Gold into PVA-PT, many labeled cells were found in the medial frontal cortex, ventral subiculum, claustrum, septum, ventral pallidum, thalamic reticular nuc., zona incerta, hypothalamus, central gray, dorsal raphe nuc., parabrachial nuc., and the laterodorsal tegmental nuc. A few cells were labeled in the medial amygdaloid nuc., amygdalohippocampal area, median raphe nuc., and the locus coeruleus. Occasional neurons were labeled in the ventral lateral geniculate nuc., pretectal area, and in the solitary nuc. and the lateral reticular nuc. in the medulla.