In order to validate 5F catheters for assessing ischemic heart disease either by the femoral and the right brachial approaches, we prospectively studied with these catheters 125 patients by means of left ventriculogram and coronary artery angiograms. Twenty-five patients were studied with pigtail and Amplatz catheters using the right brachial approach (group I) and 100 patients were studied by the femoral route with pigtail and Judkins catheters (group II). Results were compared to those obtained in a control group of 100 patients prospectively studied by the femoral route with 8F catheters (group III). The following parameters were analyzed: need to change the initially elected catheter diameter or/and artery approach; technical difficulty for obtaining left ventriculogram, left coronary artery, and right coronary artery angiograms; total time of X-ray exposure; quality image of left ventriculograms; incidence of arterial puncture related hematomas or total arterial occlusion; and duration of local compression after sheath removal. There were no differences between groups I and II except for the arterial compression time (p less than 0.0001), and the X-ray exposure time (p = 0.02); both were longer in patients studied by the brachial approach (group I). Whatever the route used, 5F showed a mild increased difficulty (brachial p = 0.001; femoral p = 0.01), and a mild decreased quality image for left coronary artery (brachial p = 0.006; femoral p less than 0.05). Among patients studied by the femoral route a reduction in mild hematomas (p less than 0.05) and in the arterial compression time (p less than 0.0001) were observed in those studied with 5F catheters.(ABSTRACT TRUNCATED AT 250 WORDS)