Recent work on the central nervous system control of penile erection i
s reviewed. Penile erection is completely dependent on commands fi om
the central nervous system. Clinical experience and experimental studi
es clearly demonstrate that systems within the spinal cord are fully c
apable of generating penile erection. Spinal erectile centers may be a
ctivated by genital afferents or by descending commands fi om higher C
NS sites. An important inhibitory pathway from the nucleus paragiganto
cellularis has been demonstrated. The inhibition of spinal sexual resp
onses is mediated by the neurotransmitter serotonin. The medial preopt
ic region has been demonstrated to be crucially involved in sexual beh
avior. It is likely that it participates in the integration of hormona
l and sensory cues necessary for sexual behavior. The medial amygdala
and paraventricular nucleus of the hypothalamus have also been shown t
o play key roles. Future CNS research may lead to new therapeutic appr
oaches as well as the avoidance of untoward sexual side effects from c
entrally acting drugs.