A serologically proven case of parainfluenza viral infection was assoc
iated with the onset and disappearance of cluster headache. The patien
t had long-standing migraine that ceased during the cluster headache p
eriod and recurred when the latter stopped. Possibly, the virus was ne
urally transmitted to the trigeminal-autonomic system, creating an inf
lammatory response that transiently precipitated cluster headache and
obliterated migraine.