OBJECTIVE To determine the projections from the lumbosacral cord to the PAG in the rhesus monkey. In three female rhesus monkeys, injections with wheat-germ agglutinin horseradish peroxidase (WGA-HRP) were made into the lumbosacral cord to determine the projection pattern of lumbosacral afferents in the periaqueductal gray (PAG). To determine the location of lumbosacral-PAG neurons, in three additional female rhesus monkeys WGA-HRP was injected into the PAG and adjacent tegmentum. The results indicate that different levels in the lumbosacral cord give rise to strong projections to different parts of the PAG and the adjacent tegmentum. FUTURE DIRECTIONS A more elaborate retrograde study will be necessary to accurately determine the location of lumbosacral neurons that project to different parts in the PAG. KEY WORDS spinomesencephalic tract, periaqueductal gray, pain, sexual behavior, micturition FUNDING Supplemental funding to RR00167