Recent reports of declining trends in mortality rates from cerebrovascular disease are based on underlying cause of death as stated on the death certificate, and may contain inaccuracies because death certificates are often completed without reference to all information in medical records, and because of changes in coding conventions and diagnostic fashion. This is a report of trends in mortality rates from cerebrovascular disease in Baltimore, Md., during 1950-1970 using data validated by reference to individual medical records from 19 hospitals. Overall accuracy of death certificate diagnoses did not change markedly during the study period. Death rates from subarachnoid hemorrhage increased in white women, but decreased in white men and in nonwhites of both sexes. Death rates from other cerebrovascular diseases declined in most sex and color groups, a result which cannot be attributed to errors in death certificate diagnoses. The increasing rates of subarachnoid hemorrhage observed in white women deserve further attention.