Afferents to the lateral posterior (pulvinar) nucleus in the rat were studied anatomically using retrograde tracing with fluorescent and horseradish peroxidase techniques. Layer V pyramidal cells in cortical areas 17 and 18a were found to project to the rostral portion of the lateral posterior nucleus (LTP) (the cortico-recipient zone). Cells in the deep superficial grey of the superior colliculus projected to the caudal portion of the LTP (the tecto-recipient zone), the posterior pole of which also received input from cortical area 36. These findings agree with the notion that the rat's LTP is functionally equivalent to regions of the feline and primate pulvinar-complex.