Amygdalostriatal projections have been studied in the monkey with the autoradiographic method for demonstrating axonal transport of tritiated amino acids. Amygdaloid fibers were found to project in a roughly topographical manner to widespread areas of the striatum and ventral striatum, including the nucleus accumbens, the striatal-like portions of the olfactory tubercle, ventral portions of the putamen and ventral and caudal parts of the caudate nucleus. The parvicellular part of the basal nucleus and the amygdalohippocampal area appear to be the major sources of fibers to the nucleus accumbens, whereas projections to the tail of the caudate nucleus seem to arise mainly from the magnocellular part of the basal nucleus. In many of these areas, the amygdalostriatal fibers are concentrated in patches.