In order to identify the effects of meteorologic factors, their changes or combinations upon attacks, 74 cerebrovascular accidents which occurred in Nago-ya, 1965 were investigated. The excess attacks of cerebral hemorrhage were found with statistical significance when temperature-humidity index and MISSENARD's effective temperature were low, when air temperature, relative humidity and atmospheric pressure were decreasing and when the grade of de-crease of air temperature became more, or when that of increase less remark-able. And cerebral hemorrhage or infarction were more frequently noted at high atmospheric pressure. Some preventive measures against cerebrovascular accidents were suggested with brief discussion on the importance of the further investigations on physiological responses to meteorologic conditions and the relative evaluation of meteorologic effects upon attacks.