The present study takes into consideration some of the symptoms comprised in the Periodic Syndrome. These include motion-sickness, cyclic vomiting, recurrent abdominal pains and paroxysmal vertigo. Particular consideration is given to the chronological and long-term aspects of such symptoms. Among 247 migraine sufferers in the pediatric age group, 173 subjects who complained of at least one of these symptoms were chosen. Results of the data show that motion-sickness is the first to manifest itself (mean age of onset 2 years), and has a tendency to continue into the headache period; cyclic vomiting appears in the third year of life, and terminates sooner than the other symptoms. At the mean age of five years abdominal pains start, and at seven, paroxysmal vertigo. Headache is the final symptom in this group. The sequentiality of such disturbances in each subject leads to the assumption that the Periodic Syndrome is the expression of a single disorder which manifests itself polymorphously as a rather precisely timed process.