The three factors other than age that are the most important determinants of stroke occurrence are (1) transient cerebral ischemic attacks (TIAs), (2) hypertension, and (3) cardiac disease.In the Rochester population study, a stroke developed during the period of observation in 36% of the patients with TIAs. Fifty-one percent of all the strokes occurred during the first year after the TIA, and 21% occurred during the first month after the first attack.Hypertensive persons have an increased incidence of each of the major atherothrombotic diseases as compared to normotensive persons.During the full 25 years of study of the Rochester population, there was a decrease from the earliest to the latest five-year period of 32% for all strokes in women and 20% in men. This may reflect treatment of this population.