Mortality rates for acute myocardial infarction (AMI) in the province of Manitoba were studied by a retrospective, randomized survey of urban and rural hospital records. Urban hospitals had formal coronary care unit (CCU). Selected rural hospitals lacked CCUs but usually possessed portable monitoring and defibrillation equipment. Twenty-seven percent of 852 cases in the study population died. The mortality rate for unequivocal AMI was 14% to 15% to both urban and rural hospitals. Patients with possible AMI had high mortality rates in both facilities (41% to 45%). Subgroup analysis of the definite AMI population failed to reveal statistically significant differences in urban vs rural mortality, although a consistent trend toward superior performance in urban centers was found. The magnitude of the potential of a rural hospital intervention program to reduce the AMI mortality nevertheless appeared to be small.