Department of Anatomy, Laval University School of Medicine, Hopital de l'Enfant-Jesus, Quebec, Canada. The striatofugal fiber system constitutes the major axis of the basal ganglia. It is along this pathway that corticostriatal information is conveyed to the major output structures of the basal ganglia (i.e., the internal segment of the globus pallidus and the pars reticulata of the substantia nigra). Although the striatofugal fiber system has been the subject of innumerable neuroanatomic studies in the past, the development of ever powerful tract-tracing methods and their application during the last few years to the analysis of the striatofugal projections in primates has shed a new light on our knowledge of the organization of this fiber system. This paper provides a brief overview of the results of some of our recent studies devoted to this issue. Our main purpose is to examine in detail the organization of the striatopallidal projections in monkeys to better delineate the anatomic substrate of information processing along the major axis of the basal ganglia.