A community-based study of 425 older African Americans assessed whether their knowledge and behaviors were consistent with current recommendations regarding out-of-hospital sudden heart attack. More than 90% of the study participants were able to recognize major symptoms of sudden heart attack such as chest pain, shortness of breath, weakness, fatigue, fainting, and sweating, and, to a lesser extent, atypical pain, nausea, lightheadedness, and unexplained anxiety. When asked what they would do first in case they witness sudden heart attack, 97% responded that they would call emergency medical services. In contrast, of the participants who actually witnessed sudden heart attack, 80% called emergency medical services, whereas 20% waited to see if the symptoms would go away; called a neighbor, relative, or a friend before contacting emergency medical services; or took the victim to the hospital. These findings show that reported behavioral intentions were satisfactory, but actual bystanders' actions were not always consistent with current recommendations regarding sudden heart attack.