The community surveillance component of the Atherosclerosis Risk in Communities (ARIC) Study is designed to estimate patterns and trends of coronary heart disease (CHD) incidence, case fatality, and mortality in four U.S. communities. Community surveillance involves ongoing review of death certificates and hospital discharge records to identify CHD events in community residents aged 35-74 years. Interviews with next of kin and questionnaires completed by physicians and medical examiners or coroners were used to collect information on deaths, and review and abstraction of hospital records were used to collect information on possible fatal and nonfatal myocardial infarctions (MIs). Events were classified using standardized criteria. The initial 2-years' experience with case ascertainment and availability of information needed for classification of events is described. Average annual age-adjusted attack rates of definite MI and CHD mortality rates for blacks in two communities and whites in the four communities are presented and compared with rates based on unvalidated hospital discharge data and vital statistics. Age-adjusted rates based on ARIC classification of definite MI were lower than those based on hospital discharge diagnosis code 410 (e.g., 5.60/1000 and 11.50/1000 among Forsyth County white men, respectively). Age-adjusted rates of definite fatal CHD based on ARIC classification were similarly lower than rates based on underlying cause of death code 410; for example, Jackson black men had rates of 2.82/1000 and 4.52/1000 for definite fatal CHD and UCOD 410-414 or 429.2, respectively.