The cardinal diagnostic features of cardiac infarction following occlusion of a coronary artery are now well known. How often each of these signs occurs, when in the course of the illness it appears, and how long it may be expected to persist are matters largely of general impression. This study was designed to furnish factual evidence on these points. In the course of the analysis, certain guides to prognosis became apparent. MATERIAL AND METHOD The case records of 50 patients with uncomplicated cardiac infarction following coronary occlusion furnish the basis of this report. All were admitted to the wards and were seen daily by at least one of us. Of the group 44 entered the hospital within four days of the acute attack, and 25 were under observation from the first day. Seventeen patients died in the hospital. Necropsy, performed on 10, confirmed the clinical diagnosis. The material was selected.