Botulinum toxin A has been used to treat a spectrum of neuromuscular diseases. In recent years, it has become an accepted treatment for dynamic facial wrinkles. Following treatment of glabella and forehead wrinkles with botulinum toxin A, 9 of 134 patients coincidentally reported improvement of tension-type headache. We have retrospectively studied this group of patients in whom improvement of facial wrinkles closely paralleled improvement of tension-type headache. This observation suggests a role for muscle action in tension-type headache and a novel treatment.