The use of small catheters for cardiac catheterization, as well as for other diagnostic and interventional procedures, can reduce iatrogenic trauma on cardiac and vascular structures. Early patient mobilization may thus reduce both patient discomfort and the length and cost of stays. The performance of 4 French catheters was evaluated in a pilot cohort of consecutive in patients who underwent coronary arteriography with the use of the femoral Judkins technique and who had no restriction to full ambulation. Patients were helped to resume full ambulation two hours after the procedure, and the femoral access site was inspected 24 hours later upon discharge. Coronary arteriography with 4 French catheters was performed in 45 patients (10 women) aged 62 +/- 10 years. In one patient with anomalous origin of the right coronary artery, selective catheterization of the coronary ostium required a catheter style available only in 5 French. In all cases, selective opacification with 4 French catheters was adequate for diagnosis. Forty-three patients were mobilized 115 +/- 10 minutes after the end of manual compression. Hematoma, bleeding or limb perfusion disturbances were absent in all cases upon inspection 22 +/- 4 hours later. This pilot experience indicates that coronary arteriography with femoral 4 French Judkins catheters is technically feasible and that patient ambulation 2 hours later is safe. This data requires confirmation in a larger patient cohort and can lead to new standards for both patient comfort and the use of hospital resources in coronary arteriography